Question

find the kinetic energy of a cricket ball of mass 500 gram moving at a speed of 30 cm second

Answer 1

Use the formula 1/2 mv^2

where mass = 0.5 kg (convert gram to kg bcz kg is an SI unit)
velocity = 0.3 m/s (simply convert cm to m since second is an SI unit there ia no need to convert it)

so you'll get

1/2 × 0.5 × 0.3^2

0.0225 J