A toy gun uses a spring to project a 4.8-g soft rubber sphere horizontally. The spring constant is 8.0 N/m, the barrel of the gun is 16 cm long, and a constant frictional force of 0.039 N exists between barrel and projectile. With what speed does the projectile leave the barrel if the spring was compressed 6.8 cm for this launch? (Assume the projectile is in contact with the barrel for the full 16 cm.) m/s

2.A 666-kg elevator starts from rest and moves upward for 2.70 s with constant acceleration until it reaches its cruising speed, 1.78 m/s.(a) What is the average power of the elevator motor during this period? hp (b) How does this amount of power compare with its power during an upward trip with constant speed? (Give the power during an upward trip with constant speed.) hp

3.A block of mass m=4.00kg is released from rest from pointand slides on the frictionless track shown in the figure below.

m B h 3.20 m 2.00 m i