39. 40. 41. In moving an object 7.0 m, 40 J of energy are expended. The average force exerted is closest to (a) 2.8 x I02 N (b) 47 N (c) 23 N (d) 5.? N (e) 0.13 N A bullet is red from a gun with a speed of 1000 cmfs. If the bullet has a mass of 0.01 kg, it possesses a kinetic energy of (a) 0.05 J (b) 0.5 J (0)1 J (d) 5 J ((3)51: 103 J Mr. Brady takes the elevator out side his office. The elevator is rising at a constant velocity. Consider these statements concerning the elevator. I) The upward force in the supporting cable is of constant magnitude. II) The kinetic energy of the elevator is constant. Ill) Its gravitational potential energy is constant. IV) Its acceleration is zero. V) The sum of its kinetic energy and its gravitational potential energy is constant. Which one of the following groups contains true statements only? (a) I, II. III, IV, and V (b) II and V only (c) IV and V only (d) I, II. and III only (e) I, II and IV only 42. An object at P originally at rest is released so that it moves down the slide. ground level Neglecting friction, which one of the following is the best expression for the speed of the object as it passes through point (3!? (a) 2g~df1x he (b) 23%; in) In + #13 (c) 252' (d) Hart'sm) (In 112)} (e) 2s 43. A potato is thrown upward. Which one of the following quantities increases as the potato rises (a) force of gravity (b) potential energy (c) kinetic energy (d) speed (e) weight 44. The strong nuclear force is carried by which mediating force? a. photons d. gluons b. muons e. bosons c. pions