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# Engineering Mechanics - PKRB: Impulse and Momentum

### Exercise

• General Questions
"Everything you can imagine is real."
- Pablo Picasso
1.

The uniform rod AB has a weight of 3 lb and is released from rest without rotating from the position shown. As it falls, the end A strikes a hook S, which provides a permanent connection. Determine the speed at which the other end B strikes the wall at C.

 A. vB4 = 14.74 ft/s B. vB4 = 20.3 ft/s C. vB4 = 22.0 ft/s D. vB4 = 12.69 ft/s

2.

Gear A has a weight of 1.5 lb, a radius of 0.2 ft, and a radius of gyration of ko = 0.13ft. The coefficient of friction between the gear rack B and the horizontal surface is = 0.3. If the rack has a weight of 0.8 lb and is initially sliding to the left with a velocity of (vB)2 = 8 ft/s to the left. Neglect friction between the rack and the gear and assume that the gear exerts only a horizontal force on the rack.

 A. M = 0.01425 lb-ft B. M = 0.00630 lb-ft C. M = 0.0622 lb-ft D. M = 0.0560 lb-ft

3.

The 50-kg cylinder has an angular velocity of 30 rad/s when it is brought into contact with the horizontal surface at C. If the coefficient of friction is c = 0.2, determine how long it takes for the cylinder to stop spinning. What force is developed at the pin A during this time? The axis of the cylinder is connected to two symmetrical links. (Only AB is shown.) For the computation, neglect the weight of the links.

 A. t = 1.529 s, A = 0 B. t = 3.06 s, A = 0 C. t = 1.529 s, A = 49.1 N D. t = 3.06 s, A = 49.1 N

4.

The uniform pole has a mass of 15 kg and falls from rest when = 90° until it strikes the edge at A, = 60°. If the pole then begins to pivot about this point after contact, determine the pole's angular velocity just after the impact. Assume that the pole does not slip at B as it falls until it strikes A.