15-87. The "stone" A used in the sport of curling slides over the ice track and strikes another “stone" B as shown. If each “stone" is smooth and has a weight of 47 lb, and the coefficient of restitution between the "stones" is e = 0.8, determine their speeds just after collision. Initially A has a velocity of 8 ft/s and B is at rest. Neglect friction. 3 ft 30 (vA)ı = 8 ft/s

(a) Compute the impulse necessary to bring to rest the 48.0 kg driver of an automobile initially moving at 20m / s? b) Find the average force on the driver if the deceleration is accomplished gradually by the application of brakes over a 11.6 s inteval? (c) Find the average force if the car is stopped in a collision that brings the driver's seat to rest in 0.100 s assuming the driver is restrained by a seat belt?

4) Two boxes are on a frictionless work surface that is 5m off the ground. The second mass on the right is double the mass of the box on the left. The box on the left has an initial speed of 10 m/s and has an elastic collision with the second box. How far does the second box travel to the right of the work surface (the horizontal distance from the right edge) before hitting the ground?

b) A vertical pile of mass 150 kg is driven 120 mm into the ground by the blow of a 1100 kg hammer, which falls through 800 mm. assuming the hammer and pile remain in contact, determine the following: i) The velocity of the hammer just before impact ii) The velocity immediately after impact iii) The resistive force of the ground, assuming it to be uniform