This print-out should have 21 questions. inelastic case Multiple-choice questions may continue on the next column or page - find all choices before answering a bullet 001 10.0 points inside B A bowling ball of mass 11.2 kg moves in a straight line at 1.72 m/s. elastic case How fast must a Ping-Pong ball of mass 2.05 g move in a straight line so that the two balls have the same momentum? no bullet Answer in units of m/s. inside B 002 10.0 points A 660 g ball strikes a wall at 12.1 m/s and What is the ratio of the flight time; i.e., rebounds at 13.3 m/s. The ball is in contact tAB ? with the wall for 0.044 s. t A'B' What is the magnitude of the average force LAB acting on the ball during the collision? Answer in units of N. 2. 1 003 10.0 points 3. LAB A constant force is exerted for a short time interval on a cart that is initially at rest on 4. LAB an air track. This force gives the cart a certain final speed. Suppose we repeat the 5. t AB experiment but, instead of starting from rest, the cart is already moving with constant speed 6. LAB 1 in the direction of the force at the moment we AB begin to apply the force. 7. LAB = 3 After we exert the same constant force for NB the same short time interval, the increase in 005 (part 2 of 2) 10.0 points the cart's speed Denote the speeds of block at point A and A' (the same point for different two cases) to be 1. is the same as when it started from rest. vA and vy respectively. 2. is equal to the square of its initial speed. 3. is equal to four times its initial speed. What is the ratio of the speeds -4? 4. is equal to two times its initial speed. 5. cannot be determined from the informa- 1. 19/k UN tion provided. 2. 1 004 (part 1 of 2) 10.0 points 3. 1 A bullet of mass Mi is fired towards a block - of mass my initially at rest at the edge of a frictionless table of height h as in the figure. 4. -A : 3 UN The initial speed of the bullet is vi. Consider 5. 4 two cases, a completely inelastic one and an elastic one, where the bullet bounces off the 6. 09 | block.7. - = 2 006 10.0 points Two pucks of equal mass collide. One puck 4. (puck A) is stationary before the collision. After the collision the puck that was initially stationary moves along in the same direction in which the puck that hit it (puck B) was initially moving. VB 5. Puck B Puck A Which of the following statements is correct if the total energy of the system is conserved during the collision (elastic collision)? 1. Both pucks slide past the point of colli- sion. 6. 2. The puck B rebounds. 3. The puck B remains at the point of colli- sion. 4. There isn't enough information to answer 7. the question. 008 10.0 points 007 10.0 points A woman of mass 54 kg jumps off the bow of a 40 kg canoe that is intially at rest. An object having an initial momentum If her velocity is 2 m/s to the right, what is that may be represented by the vector be- the velocity of the canoe after she jumps? low strikes an object that is initially at rest. Answer in units of m/si. 009 10.0 points Which of the following sets of vectors may You are given two carts, A and B. They look represent the momenta of the two objects af- identical, and you are told that they are made ter the collision? of the same material. You place A at rest on Note carefully: The original vector above and the following vectors are ALL DRAWN an air track and give B a constant velocity di- TO THE SAME LENGTH SCALE. rected to the right so that it collides elastically with A. After the collision, both carts move to the right, the velocity of B being smaller than what it was before the collision. What do you conclude? 1. 1. Cart A is hollow 2. Cart B is hollow 3. need more information 2. 4. The two carts are identical 3. 010 10.0 points A compact car and a large truck collide headon and stick together. between each block and the surface is 0.3. The Which undergoes the larger change in the two blocks collide, stick together, and move magnitude of momentum? to the right. Remember that the spring is not attached to the 9 kg block. 1. The momentum change is the same for Find the speed of the 9 kg block just before both vehicles. it collides with the 2 kg block. 2. Can't tell without knowing the final ve- Answer in units of m/s. locity of the combined mass. 3. car 014 (part 3 of 4) 10.0 points 4. truck Find the final speed of both blocks (stuck together) just after they collide. 011 10.0 points Answer in units of m/s. A grocery shopper tosses a(n) 8.0 kg bag of rice into a stationary 19.4 kg grocery cart. 015 (part 4 of 4) 10.0 points The bag hits the cart with a horizontal speed Find the horizontal distance the blocks move of 6.6 m/s toward the front of the cart. before coming to rest. What is the final speed of the cart and bag? Answer in units of m. Answer in units of m/s. 016 (part 1 of 2) 10.0 points 012 (part 1 of 4) 10.0 points A neutron in a reactor makes an elastic head- A massless spring with force constant on collision with the nucleus of an atom ini- 670 N/m is fastened at its left end to a vertical tially at rest. wall, as shown below. Assume: The mass of the atomic nucleus is The acceleration of gravity is 9.8 m/s2 about 11.4 the mass of the neutron. 670 N/m What fraction of the neutron's kinetic en- 000080808080 9 kg 2 kg ergy is transferred to the atomic nucleus? 017 (part 2 of 2) 10.0 points Initially, the 9 kg block and 2 kg block rest If the initial kinetic energy of the neutron is on a horizontal surface with the 9 kg block in 5.8 x 10 13 J, find its final kinetic energy. contact with the spring (but not compressing Answer in units of J. it) and with the 2 kg block in contact with the 9 kg block. The 9 kg block is then moved to 018 (part 1 of 2) 10.0 points the left, compressing the spring a distance of A jet aircraft is traveling at 273 m/s in hor- 0.3 m, and held in place while the 2 kg block izontal flight. The engine takes in air at a remains at rest as shown below. rate of 115 kg/s and burns fuel at a rate of k 0.3 m 4.72 kg/s. The exhaust gases are ejected at 420 m/s relative to the aircraft. 9 kg 2 kg Find the thrust of the jet engine. Answer in units of N. Determine the elastic energy U stored in 019 (part 2 of 2) 10.0 points the compressed spring. Find the delivered power. Answer in units of J. Answer in units of W. 013 (part 2 of 4) 10.0 points 020 10.0 points The 9 kg block is then released and accelerates A(n) 71.1 kg astronaut becomes separated to the right, toward the 2 kg block. The from the shuttle, while on a space walk. She surface is rough and the coefficient of frictionfinds herself 58.5 m away from the shuttle and moving with zero speed relative to the shuttle. She has a(n) 0.681 kg camera in her hand and decides to get back to the shuttle by throwing the camera at a speed of 12 m/s in the direction away from the shuttle. How long will it take for her to reach the shuttle? Answer in minutes. 1. 9.755 min 2. 8.059 min 3. 10.18 min 4. 11.03 min 5. 8.483 min 6. 10.60 min 7. 11.45 min 8. 8.907 min 9. 11.88 min 10. 9.331 min 021 10.0 points A rocket burns fuel at a rate of 294 kg/s and exhausts the gas at a relative speed of 6 km/s. Find the thrust of the rocket. Answer in units of MN