Newton’s 2nd Law: Class Work
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dynamics-chapter-problems-3-2012-07-18, dynamics-chapter-problems-3-2012-07-18
| General Problems
Class Work A train with a mass of 25000 kg increases its speed from 10 m/s to 25 m/s in 20 seconds. Assume that the acceleration is constant and that you can neglect friction. Find the acceleration of the train Find the distance traveled during this 20 s? Draw a free- body diagram for the train; Find the average net force supplied by the locomotive. Homework A 150 kg motorcycle starts from rest and accelerates at a constant rate along a distance of 350m. The applied force is 250 N and the coefficient of kinetic friction is 0.03. Draw a free-body diagram for the motorcycle showing all applied forces to scale. Next to that diagram show the direction of the acceleration; Find the net force applied to the motorcycle; Find the acceleration of the motorcycle; What is its speed at the end of 350 m? Find the elapsed time of this acceleration. Class Work Two blocks, with masses m1 = 400 g and m2 = 600 g, are connected by a string and lie on a frictionless tabletop. A force F = 3.5 N is applied to block m2. Draw a free-body diagram for each block showing all applied forces to scale. Next to each diagram show the direction of the acceleration of that object. Find the acceleration of each object. Find the tension force in the string between two objects. Homework Two boxes are placed on a horizontal frictionless surface, as shown above. Box A has a mass of 10 kg and box B has a mass of 16 kg. A force of 54 N is pushing box A. Draw a free-body diagram for each block showing all applied forces to scale. Next to each diagram show the direction of the acceleration of that object. Find the acceleration of the system of two boxes. Find the force of contact that each box exerts on its neighbor. Class Work A 12 kg load hangs from one end of a rope that passes over a small frictionless pulley. A 15 kg counterweight is suspended from the other end of the rope. The system is released from rest. Draw a free-body diagram for each object showing all applied forces in relative scale. Next to each diagram show the direction of the acceleration of that object. Find the acceleration each mass. What is the tension force in the rope? What distance does the 12 kg load move in the first 3 s? What is the velocity of 15 kg mass at the end of 5 s? Homework The masses of blocks A and B are 4.5 kg and 3.7 kg respectively. The blocks are initially at rest and are connected by a massless string passing over a massless, frictionless pulley. The system is released from rest. Draw a free-body diagram for each block showing all the applied forces in relative scale. Next to each diagram show the expected direction of acceleration. What is the acceleration of blocks? What is the tension force in the rope? How high will the 3.7 kg block move in the first 2.5 s? Find the speed of the 4.5 kg block at the end of 5th second. Class Work A 500 g block lies on a horizontal tabletop. The coefficient of kinetic friction between the block and the surface is 0.25. The block is connected by a massless string to the second block with a mass of 300 g. The string passes over a light frictionless pulley as shown above. The system is released from rest. Draw clearly labeled free-body diagrams for each of the 500 g and the 300g masses. Include all forces and draw them to relative scale. Draw the expected direction of acceleration next to each free-body diagram. Use Newton’s Second Law to write an equation for the 500 g mass. Use Newton’s Second Law to write an equation for the 300 g mass. Find the acceleration of the system by simultaneously solving the system of two equations. What is the tension force in the string? Download 206.85 Kb. Share with your friends:
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