## 1 MECE2320U-THERMODYNAMICS HOMEWORK # 5 Instructor: Dr. Ibrahim Dincer Assignment Date: Thursday, 22 October 2015 Assignment Type: Individual Due Date: Thursday, 29 October 2015 (3.00 pm latest, leave in dropbox 8) 1) As shown in figure, the inlet and outlet conditions of a steam turbine are given. The heat loss from turbine is 35 kJ per kg of steam. a) Show all the state points on T-v diagram b) Write mass and energy balance equations c) Calculate the turbine work 2) As shown in figure, refrigerant R134a enters to a compressor. Write both mass and energy balance equations. Calculate the compressor work and the mass flow rate of refrigerant. 3) As shown in figure, the heat exchanger uses the heat of hot exhaust gases to produce steam. Where, 15% of heat is lost to the surroundings. Exhaust gases enters the heat exchanger at 500°C. Water enters at 15°C as saturated liquid and exit at saturated vapor at 2 MPa. Mass flow rate of water is 0.025 kg/s, and for exhaust gases, it is 0.42 kg/s. The specific heat for exhaust gases is 1.045 kJ/kg K, which can be treated as ideal gas. 1 Turbine 2 ? 1 = 1 ??/? ?1 = 1 ??? ?1 = 300 ℃ ?1 = 40 ?/? ? ??? =? ????? = 35 ??/?? ?2 = 150 ??? ?2 = 0.9 ?2 = 180 ?/? 1 Compressor 2 ???? ???? = 1.3 ?3/??? ?1 = 100 ??? ?1 = −20 ℃ ? ?? =? ? ???? = 3 ?? ?2 = 800 ??? ?2 = 60 ℃ 2 a) Write mass and energy balance equations. b) Calculate the rate of heat transfer to the water. c) Calculate the exhaust gases exit temperature. 4) As shown in figure, two refrigerant R134a streams mix in a mixing chamber. If the mass flow rate of cold stream is twice that of the hot stream. a) Write mass and energy balance equations. b) Calculate the temperature of the mixture at the exit of the mixing chamber c) Calculate the quality at the exit of the mixing chamber 5) As shown in figure, an air conditioning system requires airflow at the main supply duct at a rate of 140 m3/min. The velocity inside circular duct is not to exceed 9 m/s. Assume that the fan converts 85% of electrical energy it consumes into kinetic energy of air. a) Write mass and energy balance equations. b) Calculate the size of electric motor require to drive the fan c) Calculate the diameter of the main duct ?2 = 1 ??? ?2 = 90 ℃ ?1 = 1 ??? ?1 = 30 ℃ ?3 =? ?3 =? 140 ?3/??? 9 ?/? Air Fan

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## Determine the maximum theoritical speed that may be achieved over a distance of 110 m by a car starting from rest assuming there is no slipping. The cofficient of static friction between the tires and pavement is 0.75 .assume (a) front-wheel drive, (b) near-wheel drive.

## 1A. You administer an IV with 3 liters of 50 mM NaCl to a person whose osmolarity is 300 mOsM and whose total body water is 30 L. Fill in the table below: 3 L of 50 mM NaCl Total body ECF ICF Solute (osmoles) Volume (L) Concentration (OsM) 1B. The same person from the previous problem instead is given 1 liter of an IV contained 250 mOsM NaCl and 50 mOsM urea. Com Total body ECF ICF Solute Volume Concentration 2. You isolate intact mitochondria as described in class and equilibrate them in a buffered solution at pH 9, containing 0.1 M KCl and ADP plus Pi but without succinate. You then collect them by centrifugation, and quickly resuspend them in a new buffer at pH 7, without KCl , but with valinomycin (a K+ ionophore). Note: the K+ rushing out will create a huge positive charge differential. a. Describe what happens to proton concentrations in the intermembrane space and the matrix at each step of the study. b. What do you predict will be the result on oxygen consumption and the production of ATP? 3. A negatively charged nutrient (equivalent charge of one electron) is actively transported from the outside to the inside of a cell membrane; i.e. a cell captures energy from the hydrolysis of ATP in order to bring a molecule from the outside of the cell, where it is present at a low concentration, to the inside of the cell, where it is present at higher concentration. If the molecular species to be transported is present at a concentration of 34.5 nM on the outside of the cell, the potential on the outside of the cell is +75 mV, the potential on the inside of the cell is -35 mV, and the efficiency at which energy from the hydrolysis of ATP is captured for this active transport process is 59%, what is the maximum concentration of the transported species that may be achieved inside the cell? 4. . ATP + H2O -> ADP + Pi G0 = -7.3 kcal/mol In a chemical system that has two different solute concentrations, the Gibbs free energy that is available to do work is: ΔG = RT ln [C1/C2], where R and T are the gas constant (2 cal/mol K) and temperature (Kelvin). C1 and C2 refer to the concentrations (e.g. molarities, M) of a solute on different sides of a membrane. (a) For a one unit difference in pH across a cellular membrane, what is the energy (in kcal/mol) that is available to do chemical work? (b) This gradient is to be used to drive the reaction synthesis of ATP from ADP and Pi. A concentration gradient of any solute has potential energy. When the solute is charged, a voltage is also established across the membrane, which also adds to the total potential energy. What fraction of the energy needed to drive the reaction is provided by the voltage across the membrane?

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## Which of the following is not true about hysterectomy? Question 41 options: There is no risk of having to repeat the procedure in months or years. There is growing concern that it can be overused as a treatment for DUB. In 50% of hysterectomies performed to treat DUB, there is no cancer present. There is no change in sexual function or sex drive after hysterectomy.

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## You and a friend each drive 42 km. You travel at 89. km/h, your friend at 94 km/h. How long will your friend wait for you at the end of the trip

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## Question 1 When using NTFS as a file system, what can be used to control the amount of hard disk space each user on the machine can have as a maximum? Answer Logical drives Extended partitions Disk quotas Security Center Question 2 Pin 1 of the floppy cable connects to pin 34 of the controller. Answer True False Question 3 What is the primary cause of hard drive failures? Answer Heat Dust Dirty laser lens Moving parts Question 4 The DBR contains the system files. Answer True False Question 5 A spanned volume requires a minimum of three hard drives. Answer True False Question 6 Which situation would not be appropriate for the use of SSDs? Answer A military operation where fast access to data is critical A medical imaging office that needs high-capacity storage A manufacturing plant with heat-sensitive equipment A research facility where noise must be kept to a minimum Question 7 Why are SSDs more susceptible than mechanical hard drives to electrostatic discharge? Answer The internal battery of the SSD provides additional current. SSDs are memory. The voltage level of the SSD is lower than a mechanical hard drive. The SSD is a more fragile component. Question 8 A motherboard has two PATA IDE connectors, A and B. A is nearer the edge than B. The IDE cable from A connects to a 500GB hard drive and then to a 200GB hard drive. The IDE cable from B connects to an R/W optical drive and then to a Blu-ray optical drive. Assuming the setup is optimal, which of the following describes the 500GB hard drive? Answer Primary slave Secondary slave Primary master Secondary master Question 9 The primary IDE motherboard connection normally uses I/O address 1F0 -1F7h and IRQ 15. Answer True False Question 10 A cable with a twist is used when installing two floppy drives. Answer True False Question 11 What does partitioning the hard drive mean? Answer Dividing the hard drive up into three different sections: one for each type of file system Preparing the drive to be mounted Giving the hard drive a drive letter and/or allowing the hard drive to be seen as more than one drive Preparing the drive for an operating system Question 12 The Network Engineering Technology departmental secretary is getting a new computer funded by a grant. The old computer is being moved by the PC technicians to give to the new program facilitator in another department. Which one of the following is most likely to be used before the program facilitator uses the computer? Answer Check Now Tool Backup Tool Disk Management Tool BitLocker Question 13 What is CHKDSK? Answer A command used to scan the disk for viruses during off hours A program used to defragment the hard drive A program used to locate and identify lost clusters A command used to verify the validity of the drive surface before installing a file system or an operating system Question 14 When a disk has been prepared to store data, it has been Answer Cleaned Tracked Enabled Formatted Question 15 Where would you go to enable a SATA port? Answer CMOS BIOS Disk Management Tool Task Manager Question 16 The Windows boot partition is the partition that must contain the majority of the operating system. Answer True False Question 17 Two considerations when adding or installing a floppy drive are an available drive bay and an available power connector. Answer True False Question 18 What is the difference between a SATA 2 and a SATA 3 hard drive? Answer The SATA 3 has a different power connector. The SATA 3 device transmits more simultaneous bits than SATA 2. The SATA 3 device transmits data faster. SATA 3 will always be a larger capacity drive. The SATA 3 device will be physically smaller. Question 19 What command would be used in Windows 7 to repair a partition table? Answer FDISK FORMAT FIXBOOT bootrec /FixMbr FIXMBR Question 20 What file system is optimized for optical media? Answer exFAT FAT32 CDFS NTFS Question 21 One of the most effective ways of increasing computer performance is to increase the size of virtual memory. Answer True False Question 22 Older PATA IDE cables and the Ultra ATA/66 cable differ by Answer Where the twist occurs The number of conductors The number of pins The number of devices they can connect to Question 23 Which of the following is NOT important in assigning SCSI IDs? Answer The hard drive that the system boots to may have a preset ID. ID priority must match the order of appearance on the SCSI chain. All devices must have unique IDs. Slower devices should have higher priority IDs. Question 24 The ATA standard is associated with the SCSI interface. Answer True False Question 25 A striped volume requires a minimum of two hard drives. Answer True False

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## Chapter 8 Practice Problems (Practice – no credit) Due: 12:59pm on Friday, April 18, 2014 You will receive no credit for items you complete after the assignment is due. Grading Policy Circular Launch A ball is launched up a semicircular chute in such a way that at the top of the chute, just before it goes into free fall, the ball has a centripetal acceleration of magnitude 2 . Part A How far from the bottom of the chute does the ball land? Your answer for the distance the ball travels from the end of the chute should contain . You did not open hints for this part. ANSWER: g R Normal Force and Centripetal Force Ranking Task A roller-coaster track has six semicircular “dips” with different radii of curvature. The same roller-coaster cart rides through each dip at a different speed. Part A For the different values given for the radius of curvature and speed , rank the magnitude of the force of the roller-coaster track on the cart at the bottom of each dip. Rank from largest to smallest. To rank items as equivalent, overlap them. You did not open hints for this part. ANSWER: D = R v Two Cars on a Curving Road Part A A small car of mass and a large car of mass drive along a highway. They approach a curve of radius . Both cars maintain the same acceleration as they travel around the curve. How does the speed of the small car compare to the speed of the large car as they round the curve? You did not open hints for this part. m 4m R a vS vL ANSWER: Part B Now assume that two identical cars of mass drive along a highway. One car approaches a curve of radius at speed . The second car approaches a curve of radius at a speed of . How does the magnitude of the net force exerted on the first car compare to the magnitude of the net force exerted on the second car? You did not open hints for this part. ANSWER: ± A Ride on the Ferris Wheel A woman rides on a Ferris wheel of radius 16 that maintains the same speed throughout its motion. To better understand physics, she takes along a digital bathroom scale (with memory) and sits on it. When she gets off the ride, she uploads the scale readings to a computer and creates a graph of scale reading versus time. Note that the graph has a minimum value of 510 and a maximum value of 666 . vS = 1 4 vL vS = 1 2 vL vS = vL vS = 2vL vS = 4vL m 2R v 6R 3v F1 F2 F1 = 1 3 F2 F1 = 3 4 F2 F1 = F2 F1 = 3F2 F1 = 27F2 m N N Part A What is the woman’s mass? Express your answer in kilograms. You did not open hints for this part. ANSWER: ± Mass on Turntable A small metal cylinder rests on a circular turntable that is rotating at a constant speed as illustrated in the diagram . The small metal cylinder has a mass of 0.20 , the coefficient of static friction between the cylinder and the turntable is 0.080, and the cylinder is located 0.15 from the center of the turntable. Take the magnitude of the acceleration due to gravity to be 9.81 . m = kg kg m m/s2 Part A What is the maximum speed that the cylinder can move along its circular path without slipping off the turntable? Express your answer numerically in meters per second to two significant figures. You did not open hints for this part. ANSWER: Score Summary: Your score on this assignment is 0%. You received 0 out of a possible total of 0 points. vmax vmax = m/s

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## Assignment 6 Due: 11:59pm on Friday, March 7, 2014 You will receive no credit for items you complete after the assignment is due. Grading Policy Conceptual Question 7.7 A small car is pushing a large truck. They are speeding up. Part A Is the force of the truck on the car larger than, smaller than, or equal to the force of the car on the truck? ANSWER: Correct Conceptual Question 7.12 The figure shows two masses at rest. The string is massless and the pulley is frictionless. The spring scale reads in . Assume that = 4 . The force of the truck on the car is larger than the force of the car on the truck. The force of the truck on the car is equal to the force of the car on the truck. The force of the truck on the car is smaller than the force of the car on the truck. kg m kg Part A What is the reading of the scale? Express your answer to one significant figure and include the appropriate units. ANSWER: Correct Problem 7.1 A weightlifter stands up at constant speed from a squatting position while holding a heavy barbell across his shoulders. Part A Draw a free-body diagram for the barbells. Draw the force vectors with their tails at the dot. The orientation of your vectors will be graded. The exact length of your vectors will not be graded but the relative length of one to the other will be graded. ANSWER: m = 4 kg Correct Part B Draw a free-body diagram for the weight lifter. Draw the force vectors with their tails at the dot. The orientation of your vectors will be graded. The exact length of your vectors will not be graded but the relative length of one to the other will be graded. ANSWER: Correct Problem 7.6 Block A in the figure is sliding down the incline. The rope is massless, and the massless pulley turns on frictionless bearings, but the surface is not frictionless. The rope and the pulley are among the interacting objects, but you’ll have to decide if they’re part of the system. Part A Draw a free-body diagram for the block A. The orientation of your vectors will be graded. The exact length of your vectors will not be graded. ANSWER: Correct Part B Draw a free-body diagram for the block B. The orientation of your vectors will be graded. The exact length of your vectors will not be graded. ANSWER: Correct A Space Walk Part A An astronaut is taking a space walk near the shuttle when her safety tether breaks. What should the astronaut do to get back to the shuttle? Hint 1. How to approach the problem Newton’s 3rd law tells us that forces occur in pairs. Within each pair, the forces, often called action and reaction, have equal magnitude and opposite direction. Which of the actions suggested in the problem will result in the force pushing the astronaut back to the shuttle? ANSWER: Correct As the astronaut throws the tool away from the shuttle, she exerts a force in the direction away from the shuttle. Then, by Newton’s 3rd law, the tool will exert an opposite force on her. Thus, as she throws the tool, a force directed toward the shuttle will act on the astronaut. Newton’s 2nd law stipulates that the astronaut would acquire an acceleration toward the shuttle. Part B Assuming that the astronaut can throw any tool with the same force, what tool should be thrown to get back to the shuttle as quickly as possible? You should consider how much mass is left behind as the object is thrown as well as the mass of the object itself. Hint 1. How to approach the problem Recall that the force acting on the astronaut is equal in magnitude and opposite in direction to the force that she exerts on the tool. Hint 2. Newton’s 2nd law Newton’s 2nd law states that . If force is held constant, then acceleration is inversely proportional to mass. For example, when the same force is applied to objects of different mass, the object with the largest mass will experience the smallest acceleration. ANSWER: Attempt to “swim” toward the shuttle. Take slow steps toward the shuttle. Take a tool from her tool belt and throw it away from the shuttle. Take the portion of the safety tether still attached to her belt and throw it toward the shuttle. F = ma Correct The force that acts on the astronaut must equal in magnitude the force that she exerts on the tool. Therefore, if she exerts the same force on any tool, the force acting on her will be independent of the mass of the tool. However, the acceleration that the astronaut would acquire is inversely proportional to her mass since she is acted upon by a constant force. If she throws the tool with the largest mass, the remaining mass (the astronaut plus her remaining tools) would be smallest—and the acceleration the greatest! Part C If the astronaut throws the tool with a force of 16.0 , what is the magnitude of the acceleration of the astronaut during the throw? Assume that the total mass of the astronaut after she throws the tool is 80.0 . Express your answer in meters per second squared. Hint 1. Find the force acting on the astronaut What is the magnitude of the force acting on the astronaut as she throws the tool? Express your answer in newtons. ANSWER: Hint 2. Newton’s 2nd law An object of mass acted upon by a net force has an acceleration given by . ANSWER: The tool with the smallest mass. The tool with the largest mass. Any tool, since the mass of the tool would make no difference. N a kg F F = 16.0 N m F a F = ma a = 0.200 m/s2 Correct Problem 7.10 Blocks with masses of 2 , 4 , and 6 are lined up in a row on a frictionless table. All three are pushed forward by a 60 force applied to the 2 block. Part A How much force does the 4 block exert on the 6 block? Express your answer to one significant figure and include the appropriate units. ANSWER: Correct Part B How much force does the 4 block exert on the 2 block? Express your answer to two significant figures and include the appropriate units. ANSWER: Correct Problem 7.9 A 1000 car pushes a 2100 truck that has a dead battery. When the driver steps on the accelerator, the drive wheels of the car push against the ground with a force of 4500 . Rolling friction can kg kg kg N kg kg kg F = 30 N kg kg F = 50 N kg kg N be neglected. Part A What is the magnitude of the force of the car on the truck? Express your answer to two significant figures and include the appropriate units. ANSWER: Correct Part B What is the magnitude of the force of the truck on the car? Express your answer to two significant figures and include the appropriate units. ANSWER: Correct Atwood Machine Special Cases An Atwood machine consists of two blocks (of masses and ) tied together with a massless rope that passes over a fixed, perfect (massless and frictionless) pulley. In this problem you’ll investigate some special cases where physical variables describing the Atwood machine take on limiting values. Often, examining special cases will simplify a problem, so that the solution may be found from inspection or from the results of a problem you’ve already seen. For all parts of this problem, take upward to be the positive direction and take the gravitational constant, , to be positive. F = 3000 N F = 3000 N m1 m2 g Part A Consider the case where and are both nonzero, and . Let be the magnitude of the tension in the rope connected to the block of mass , and let be the magnitude of the tension in the rope connected to the block of mass . Which of the following statements is true? ANSWER: Correct Part B Now, consider the special case where the block of mass is not present. Find the magnitude, , of the tension in the rope. Try to do this without equations; instead, think about the physical consequences. Hint 1. How to approach the problem If the block of mass is not present, and the rope connecting the two blocks is massless, will the motion of the block of mass be any different from free fall? Hint 2. Which physical law to use Use Newton’s 2nd law on the block of mass . m1 m2 m2 > m1 T1 m1 T2 m2 is always equal to . is greater than by an amount independent of velocity. is greater than but the difference decreases as the blocks increase in velocity. There is not enough information to determine the relationship between and . T1 T2 T2 T1 T2 T1 T1 T2 m1 T m1 m2 m2 ANSWER: Correct Part C For the same special case (the block of mass not present), what is the acceleration of the block of mass ? Express your answer in terms of , and remember that an upward acceleration should be positive. ANSWER: Correct Part D Next, consider the special case where only the block of mass is present. Find the magnitude, , of the tension in the rope. ANSWER: Correct Part E For the same special case (the block of mass not present) what is the acceleration of the end of the rope where the block of mass would have been attached? Express your answer in terms of , and remember that an upward acceleration should be positive. T = 0 m1 m2 g a2 = -9.80 m1 T T = 0 m2 m2 g ANSWER: Correct Part F Next, consider the special case . What is the magnitude of the tension in the rope connecting the two blocks? Use the variable in your answer instead of or . ANSWER: Correct Part G For the same special case ( ), what is the acceleration of the block of mass ? ANSWER: Correct Part H Finally, suppose , while remains finite. What value does the the magnitude of the tension approach? Hint 1. Acceleration of block of mass a2 = 9.80 m1 = m2 = m m m1 m2 T = mg m1 = m2 = m m2 a2 = 0 m1 m2 m1 As becomes large, the finite tension will have a neglible effect on the acceleration, . If you ignore , you can pretend the rope is gone without changing your results for . As , what value does approach? ANSWER: Hint 2. Acceleration of block of mass As , what value will the acceleration of the block of mass approach? ANSWER: Hint 3. Net force on block of mass What is the magnitude of the net force on the block of mass . Express your answer in terms of , , , and any other given quantities. Take the upward direction to be positive. ANSWER: ANSWER: Correct Imagining what would happen if one or more of the variables approached infinity is often a good way to investigate the behavior of a system. m1 T a1 T a1 m1 a1 a1 = -9.80 m2 m1 m2 a2 = 9.80 m2 Fnet m2 T m2 g Fnet = T − m2g T = 2m2g Problem 7.17 A 5.9 rope hangs from the ceiling. Part A What is the tension at the midpoint of the rope? Express your answer to two significant figures and include the appropriate units. ANSWER: Correct Problem 7.23 The sled dog in figure drags sleds A and B across the snow. The coefficient of friction between the sleds and the snow is 0.10. Part A If the tension in rope 1 is 100 , what is the tension in rope 2? Express your answer to two significant figures and include the appropriate units. ANSWER: kg T = 29 N N T2 = 180 N Correct Enhanced EOC: Problem 7.31 Two packages at UPS start sliding down the ramp shown in the figure. Package A has a mass of 4.50 and a coefficient of kinetic friction of 0.200. Package B has a mass of 11.0 and a coefficient of kinetic friction of 0.150. You may want to review ( pages 177 – 181) . For help with math skills, you may want to review: Vector Components Part A How long does it take package A to reach the bottom? Express your answer with the appropriate units. Hint 1. How to approach the problem Start by drawing force identification diagrams for package A and package B separately. What are the four forces acting on each block? Which of the forces are related by Newton’s third law? Draw separate free-body diagrams for block A and for block B. What is a good coordinate system to use to describe the motion of the blocks down the ramp? Label your coordinate system on the free-body diagram. In your coordinate system, compute the x and y components of each force on block A. What are the x and y components of the net force on block A? What are the x and y components of the net force on block B? Given that the coefficient of friction of block A is greater than the coefficient of friction of block B, do you think the blocks will stay together as they slide down the ramp? Assuming that they do stay together, how is the acceleration of the two blocks related? (We can check this assumption later.) Using the components of the forces and Newton’s second law, what is the acceleration of the blocks? What is the initial velocity of the blocks? Given the initial velocity and the acceleration, 20 kg kg how long does it take block A to go the given distance? To check that the blocks do indeed stay together, solve for the force of block B on block A. If the force is directed toward the bottom of the ramp, then the blocks stay together. ANSWER: Correct Problem 7.33 The 1.0 kg block in the figure is tied to the wall with a rope. It sits on top of the 2.0 kg block. The lower block is pulled to the right with a tension force of 20 N. The coefficient of kinetic friction at both the lower and upper surfaces of the 2.0 kg block is = 0.420. 1.48 s μk Part A What is the tension in the rope holding the 1.0 kg block to the wall? Express your answer with the appropriate units. ANSWER: Correct Part B What is the acceleration of the 2.0 kg block? Express your answer with the appropriate units. ANSWER: Correct Problem 7.38 The 100 kg block in figure takes 5.60 to reach the floor after being released from rest. 4.12 N 1.77 m s2 s Part A What is the mass of the block on the left? Express your answer with the appropriate units. ANSWER: Correct Problem 7.41 Figure shows a block of mass m resting on a 20 slope. The block has coefficients of friction 0.82 and 0.51 with the surface. It is connected via a massless string over a massless, frictionless pulley to a hanging block of mass 2.0 . Part A What is the minimum mass that will stick and not slip? 98.7 kg kg m Express your answer to three significant figures and include the appropriate units. ANSWER: Correct If you need to use the rounded answer you submitted here in a subsequent part, instead use the full precision answer and only round as a final step before submitting an answer. Part B If this minimum mass is nudged ever so slightly, it will start being pulled up the incline. What acceleration will it have? Express your answer to three significant figures and include the appropriate units. ANSWER: Correct Problem 7.46 A house painter uses the chair and pulley arrangement of the figure to lift himself up the side of a house. The painter’s mass is 75 and the chair’s mass is 12 . m = 1.80 kg a = 1.35 m s2 kg kg Part A With what force must he pull down on the rope in order to accelerate upward at 0.22 ? Express your answer to two significant figures and include the appropriate units. ANSWER: Correct Score Summary: Your score on this assignment is 98.6%. You received 104.5 out of a possible total of 106 points. m/s2 F = 440 N

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