Work Energy

A ball whose kinetic energy is E, is projected at an angle of 45° to the horizontal. The kinetic energy of the ball at the highest point of its flight will be

  1. 0
  2. E
  3. E/2
  4. E/√2

Solution

Kinetic Energy, E = ½mv2

At the highest point, vertical component of velocity becomes zero and only the horizontal component is left that is given by

ux = u cosθ

θ = 45°, so cosθ = 1/√2

ux = u/√2

Kinetic energy E at the highest point = ½m(u/√2)2 = E/2

The correct option is C.