18. The following show that potential energy being transformed into kinetic energy EXCEPT: A. a man climbing a CENECO post B. a battery-operated toothbrush C. a baseball thrown vertically upward D. a spring-controlled door that is suddenly pushed open 19. You push against a rock with a force of 100 Newtons for 20 seconds. If the rock does not move, how much work in joules have you done? A. 2000 J B. B. 5 J C. C. 1 J D. D. 0 J 20. In which situation is there work done on the system? A. a basket being lifted B. a boy pushing against the wall C. a man carrying a bag of cement on his shoulder D. a weightlifter holding a barbell in the air 21. In a marathon, the winner and the runner-up have the same mass. Compared with the runner-up, the winner has more A. energy B. B. force C. C. power D. D. work 22. Pauline, a skater who is moving at high speed needs a certain amount of force to stop her. When will more stopping force be needed? A. if she has more mass B. if she has less stopping distance C. if she has more momentum D. D. all of the above 23. In Newton's Third Law of Motion, the action and reaction forces A. act on the same body B. act on different bodies C. are not necessarily equal D. are inversely proportional 24. A free falling body is one that is acted upon by no forces other than A. air resistance B. its own speed C. gravity D. speed of the wind 25. Which of the following statements is NOT true about projectile motion? A. Horizontal velocity of projectiles is constant. B. It is a combination of two independent motions - vertical and horizontal. C. The motion of the projectile released vertically downward is accelerated. D. Both horizontal and vertical velocities are constant. 26. The kinetic energy of the body is dependent upon its A. acceleration B. height C. velocity D. weight