A100-kg running back runs at 5 m/s into a stationary linebacker. it takes 0.5 s for the running back to be completely stopped. find the magnitude of force exerted on the running back during the collision.

Arod of some material 0.20 m long elongates 0.20 mm on heating from 21 to 120°c. determine the value of the linear coefficient of thermal expansion [in (degrees c)^-1] for this material.

If you held a stone over the mouth of a well and then let it go , what would happen to the stone? explain your answer.

Which of the following describe possible scenarios? a) an object has zero instantaneous velocity and non-zero acceleration. b) an object has negative acceleration and is speeding up. c) an object has positive acceleration and constant velocity. d) an object has positive velocity and zero acceleration. e) an object has increasing positive position and negative velocity. f) an object has decreasing positive position and negative acceleration.