26. A 20 g ball of clay travelling east at 3.0 m/s collides with a 30 g ball of clay travelling north at 2.0 m/s. What are the speed and the direction of the resulting 50 g ball of clay? Give your answer as an angle north of east. (ans-45 north of east at 1.7 m/s) 27. A particle moving to the left is slowed by a force pusing t othe right. Is the work done on the particle positive or negative? Or is there not enough information to tell? Expain. 28. Evaluate the dot product if a. A=3i+4j andB=2i6j b. N M m 1 - E 1i? E _'3 l .sz I i ' l i 29. A 1.0 kg object has the potential energy shown in the graph. U (I) 2 l D x (m) o I 2 3 4 a. The object starts from rest at x = 0 In. What is its speed at X: 3 m? b. Draw a force-versus-position graph showing the force Fx acting on the Object as it moves from X = 0 m to x = 4 m. Include an appropriate numerical scale on the force axis. mm o 2(th I 2 J 4 c. Use the work-kinetic energy theorem to nd the object's speed at x = 3 m if it starts from rest at 0 m. 30. a. How much work does an elevator motor do to lift a 1000 kg elevator a height of 100 m? b. How much power must the motor supply to do this in 50 s at constant speed? 31. a. A 50 g ice cube can slide without friction up and down a 30 slope. The ice cube is pressed against a spring at the bottom of the slope, compressing the spring 10 c. the spring constant is 25 N/m. When the ice cube is released, what total distance will it travel up the slope before reversing direction? (ans- 0.51 m) b. The ice cube is replaced by 50 g plastic cube whose coefficient of kinetic friction is 0.20. How far will the plastic cube travel up the slope? Use work and energy. (ans 0.38 m)