Answer the following questions for projectile motion on level ground assuming negligible air resistance (the initial angle being neither 0º nor 90º): (a) Is the velocity ever zero? (b) When is the velocity a minimum? A maximum? (c) Can the velocity ever be the same as the initial velocity at a time other than at t =0? (d) Can the speed ever be the same as the initial speed at a time other than at t =0?

a ) The velocity will never be zero . The velocity will be minimum at the highest point of projectile, which will be equal to the horizontal component of the initial velocity.

b ) The velocity will be minimum when its kinetic energy will be minimum . Kinetic energy will be minimum when its potential energy will be maximum.

Its potential energy will be maximum at the highest point so velocity will be minimum at the highest point.

c ) Velocity will never be the same as initial velocity because constant force of gravitation is acting on the projectile all the time.

d ) At the moment when the projectile returns back and hits the ground, the speed becomes equal to the initial speed ( at t = 0 ) because its kinetic energy becomes the same as initial energy , the height becoming zero.