Question

A ball of mass 1 kg is dropped from a tower. Find power of gravitational force at time t=2s. Take g=10m//s^(2).

Answer 1

The power of gravitational force is 200 W

Explanation:

Given :

Mass of ball $m = 1$ Kg

Time $t = 2$ sec

Gravitational acceleration $g = 10\frac{m}{s^{2} }$

From kinematics equation

velocity of ball is given by,

  $v = v_{o} + gt$

Where $v_{o} = 0$ initial velocity

  $v = 10 \times 2 = 20\frac{m}{s}$

Gravitational force act on ball is given by,

 $F = mg$

 $F = 10 \times 1 = 10$ N

Since power is given by,

 $P = Fv \cos \theta$

Where $\cos \theta = 1$ because angle between force and velocity is zero.

$P = 10 \times 20 = 200$ W