6.7 · Two blocks are con- Figure E6.7 nected by a very light string passing over a massless and frictionless pulley (Fig. E6.7). Traveling at constant speed, the 20.0-N block moves 75.0 cm to the right and the 12.0-N block moves 75.0 cm down- 20.0 12.0 N ward. How much work is done (a) on the 12.0-N block by (i) gravity and (ii) the tension in the string? (b) How much work is done on the 20.0-N block by (i) gravity, (ii) the tension in the string, (iii) friction, and (iv) the normal force? (c) Find the total work done on each block.
6.7 Two blocks are con- Figure E6.7 nected by a very lght string passing over a massiess and nctoniess puliey (Fg. ./). 00 the 20.0-N block moves 75.0 cm to the right and the 12.0-N block moves 75.0 cm down- ward. How much work is done (a) on the 12.0-N block by () gravity and (i) the tension in the string? (b) How much work is done on the 20.0-N blockby normal ocer c) Find me totar wok done on cach oiock, 6.20 of 6.20 an 18.0-m-tall A 4.80-Kg Wilerero rppeu Test rom the room (a) Calculate the work done by uravitv n the wrl its displacement from the roof to the ground. (h) Just before strikes the ground, what is the watermelon's () kinctic energy and (i) speed? (C) Which of the answers in parts (a) and (b) would be different if there were appreciable air resistance? 740 7.40 A 2.00-kg block is pushed against a spring with negligible mass and force constant k = 400 N/m, compressing it 0.220 m. When the block is released, it moves along a trictionless, hori- Ontal surlace and then up a Irictionless incne wilh slope 37.0 (Fig. P7.40). (a) What is the speed of the block as it slides along the horizontal surface after having left the spring? (6) How fat does the block travel up the incline before starting to slide back down? igure P.a0 k= 400 N/m 2.00 kg w.H 37.0 0220 m 7.60 7.60 CP A sled with rider having a combined mass of 125 kg travels over a perfectly smooth icy hill (Fig. P7.60). How lar does the sled land from the foot of the clifr?
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