When an object has its motion changed, the cause is generally
a. an external force
b. an internal force
c. an existential force
d. an interval force

Ababy stroller is a rest on top of a hill which is 10 m high. the stroller and baby have a mass of 20 kg. what is the potential energy of the baby and stroller?

20. threshold braking in the vehicle's braking system occurs when a. the brake pedal is pushed, heel on floorboard, with full foot pressure. b. the brakes are exerting full braking power, without traction loss. c. the driver begins pushing down the brake pedal, with moderate slowdown. d. the brakes just begin to take hold with a gradual slowdown.

Calculate the mass of an object that has a momentum of 100kg x m/sec and velocity of 4 m/sec