Initial velocity of the rock is m/sec.

Height of the rock after sec is given by .

The velocity is defined as rate of change of height.

The velocity   is defined as  .

Find the velocity of the rock at .

Height  .

m/sec. 

(a)

Find the Velocity after time sec.

Velocity of the rock after one second m/sec.  

(b)

Find the velocity at time sec.

Velocity of the rock after one second m/sec. 

(c)

Find the time at which the rock will hit the surface.

or

or

or

Rock will hit surface at sec.

(d)

Velocity of the rock when it hits the surface is .

  m/sec.

(a) The Velocity at time sec is m/sec.

(b) The Velocity at time is m/sec.

(c) Rock will hit surface at sec.

(d) Velocity of the rock when it hits the surface is m/sec.