Question

A golf pro has 2100 J of kinetic energy and swings his driver which weighs .75 kg. What is the speed of his swing?

Answer 1

Answer : The correct answer is 74.83 m/s .

The kinetic energy is energy possessed by any mass which is moving or have some speed . It is product of mass and velocity . It is expressed as :

$KE = \frac{1}{2} * m* v^2$

Where KE = kinetic energy in J or $kg\frac{m^2}{s^2}$ m = mass in Kg v = speed in m/s²

Unit of KE is Joules (J) .

Givne : KE = 2100 J mass = 0.75 kg v = ?

Plugging value in KE formula =>

$2100 J = \frac{1}{2} * 0.75 Kg * v^2$

$2100 J = 0.375 Kg * v^2$

Dividing both side by 0.375 kg =>

$\frac{2100 J}{0.375 Kg} = \frac{0.375 Kg}{0.375 Kg } * v^2$

$v^2 = 5600 \frac{m^2}{s^2}$

$v= 74.83 \frac{m}{s}$

Answer 2

The speed of his swing is 56 m/s