Physics (Mechanics) Revision Examination
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This document contains a monthly physics examination with 10 multiple-choice questions covering topics in mechanics, including: 1) Finding the acceleration and tension in a system with two masses connected by a cord over a pulley. 2) Calculating the velocity of a baseball thrown from a moving train. 3) Determining the reading of a spring scale in an accelerating elevator. 4) Using the system approach to find the acceleration and tension in a system with two masses connected by a string over a pulley. 5) Calculating the launch speed of a grasshopper that reaches a maximum height at a 45 degree angle.
Physics (Mechanics) Revision Examination
- 1. Advance level Physics T.M.Ramanan, B.Sc (Hons) in Physics Monthly Examination- February 2016 Mechanics g=10Nkg-1 Time: 1hour 1. Two objects of mass m1 and m2, with m2 > m1, are connected by a light, inextensible cord and hangover a frictionless pulley, Cord and pulley have negligible mass. Find the magnitude of the acceleration of the system and the tension in the cord. 2. A train is traveling with a speed of 15.0 m/s relative to Earth. A passenger standing at the rear of the train pitches a baseball with a speed of 15.0 m/s relative to the train off the back end, in the direction opposite the motion of the train. What is the velocity of the baseball relative to Earth? 3. A man weighs a fish with a spring scale attached to the ceiling of an elevator. While the elevator is at rest, he measures a weight of 40.0 N. What weight does the scale read if the elevator accelerates upward at 2.00 ms-2 ? 4. A block with mass m1 is4.00 kg and a ball with mass m2 is 7.00 kg are connected by a light string that passes over a frictionless pulley, as shown in Figure. The coefficient of kinetic friction between the block and the surface is 0.300. a. Find the acceleration of the two objects by using the system approach. b. Find the tension in the string. 5. A powerful grasshopper launches itself at an angle of 45° above the horizontal and rises to a maximum height of 1.00 m during the leap. (See Figure) With what speed vi did it leave the ground? (Neglect air resistance) 6. A 0.400-kg bead slides on a curved wire, starting from rest at point A in Figure. If the wire is frictionless, find the speed of the bead at B and at C. 7. The ballistic pendulum is a device used to measure the speed of a fast-moving projectile such as a bullet. The bullet is fired into a large block of wood suspended from some light wires. The bullet is stopped by the block, and the entire system swings up to a height h. It is possible to obtain the initial speed of the bullet by measuring h and the two masses. As an example of the technique, assume that the mass of the bullet, m1, is 5.00 g, the mass of the pendulum, m2, is 1.000 kg, and h is 5.00 cm. Find the initial speed of the bullet, v1i .
- 2. Advance level Physics T.M.Ramanan, B.Sc (Hons) in Physics 8. A 3.00-kg steel ball strikes a massive wall at 10.0 m/s at an angle of 60.0° with the plane of the wall. It bounces off the wall with the same speed and angle. If the ball is in contact with the wall for 0.200 s, what is the average force exerted by the wall on the ball? 9. A ball of mass M and radius R starts from rest at a height of 2.00 m and rolls down a 300 slope. What is the linear speed of the ball when it leaves the incline? (Assume that the ball rolls without slipping) 10. An airplane has wings, each with area 4.00 m2 , designed so that air flows over the top of the wing at 245 m/s and underneath the wing at 222 m/s. Find the mass of the airplane such that the lift on the plane will support its weight, assuming the force from the pressure difference across the wings is directed straight upwards.