College Physics with MasteringPhysics 7th Edition by Jerry Wilson,Anthony Buffa,Bo Lou

تمرين 72

A 0.455-kg soccer ball is kicked off level ground at an angle of 40° with an initial speed of 30.0 m/s. Neglecting air resistance, (a) at its maximum height off the ground, its kinetic energy will be (1) less than its value at launch, but not zero, (2) more than its value at launch, (3) zero. Explain. (b) Determine its kinetic energy when it is at its maximum height above the ground and compare it to the kinetic energy at launch. [ Hint : What is its velocity at the top of its arc Review projectile motion if necessary.]