Circle correct course: PHYS 1P21 or PHYS 1P91 Name: Student #: BROCK UNIVERSITY Test 6: June 2016 Number of pages: 6 Course: PHYS 1P21/1P91 Number of students: 111 Examination date: 14 June 2016 Time of Examination: 14:30 15:20 Instructor: S. D Agostino A non-graphics, non-programmable electronic calculator is allowed. A formula sheet is attached. No other aids are allowed. Solve all problems in the space provided. Total number of points: 20 For the multiple-choice questions, circle the label for the best response in each case, using a pencil or dark pen. DO NOT WRITE THE LETTERS CORRESPONDING TO YOUR ANSWERS FOR THE MULTIPLE-CHOICE QUESTIONS ON THE TEST PAPER. Do not use brightly coloured pens or highlighters to indicate your answers. 1. [1 point] Blocks A, B, and C move to the right along frictionless, horizontal surfaces. Force F A acts on Block A, force F B acts on Block B, and force F C acts on Block C. The magnitudes of the three forces are the same, but their directions are different: F A acts downwards and to the right, F B acts directly to the right, and F C acts directly downwards. Which force does the most work if the displacements of the three blocks are equal? (a) F A (b) F B (c) F C (d) [There is not enough information.] 2. [1 point] A satellite of mass 243 kg orbits the Earth at a constant speed in a circular orbit. The work done by the Earth on the satellite is (a) directed towards the centre of the circular orbit. (b) positive. (c) zero. (d) negative. (e) [Both (a) and (b) are correct.] (f) [Both (a) and (c) are correct.] (g) [Both (a) and (d) are correct.]
3. [1 point] An object moves to the right at a constant speed. The only two forces acting on the object are F 1, directed to the right, and F 2, directed to the left. The work done by F 1 on the object is W 1, and the work done by F 2 on the object is W 2. (a) W 1 > W 2 (b) W 1 = W 2 (c) W 1 < W 2 (d) W 1 + W 2 = 0 (e) [Not enough information is given.] 4. [1 point] In which one of the following situations is it not possible for mechanical energy to be conserved, even if friction and air resistance are negligible? (a) A car moves up a hill, its speed continually decreasing as it moves. (b) A car moves down a hill, its speed continually increasing as it moves. (c) A car moves along level ground at a constant speed. (d) A car moves up a hill at a constant speed. (e) [Mechanical energy might possibly be conserved in all of the above situations.] 5. [1 point] Blocks A and B have the same mass and move to the right along frictionless, horizontal surfaces. Force F A acts on Block A and force F B acts on Block B. The magnitudes and directions of the two forces are the same. Blocks A and B both start from rest, and both achieve the same final speeds, but Block A achieves this in less time than Block B. How does the power P A delivered by force F A acting on Block A compare with the power P B delivered by force F B acting on Block B? (a) P A > P B (b) P A = P B (c) P A < P B (d) [There is not enough information.]
6. An object of mass 5.2 kg moving in a straight line has an initial velocity of 4.7 m/s and a constant acceleration of 2.9 m/s 2. (a) [2 points] Determine the speed of the object after 7 s. (b) [2 points] Determine the work done on the object by the net external force acting on it. (c) [2 points] Determine the power delivered by the net external force.
7. [3 points] A slingshot fires a pebble from the top of a building at a speed of 14.0 m/s. The building is 31.0 m tall. Ignoring air resistance, determine the pebble s impact speed when it hits the ground.
8. [3 points] A transport truck is coasting downhill along a mountain highway when its brakes fail. The driver pulls onto a runaway-truck ramp that is inclined at an angle of 14.0 above the horizontal. The truck coasts to a stop after travelling 154 m along the ramp. Determine the initial speed of the truck, assuming that air resistance and friction can be ignored.
9. [3 points] Two pole-vaulters clear the bar at the same height. The first lands at a speed of 8.90 m/s and the second lands at a speed of 9.00 m/s. The first vaulter clears the bar at a speed of 1.00 m/s. Ignore air resistance and friction and determine the speed at which the second vaulter clears the bar.