What is the mass of earth?

Find the retardation with which a train moving at $108 \mathrm{km}/\mathrm{hr}$ is brought to rest in $12$ seconds.

What is the direction of acceleration?

Why does a boxer move his head backwards when his opponent blows a punch?

Define Newton's second law.

Define one newton.

While catching a fast moving ball, fielder gradually pulls his hand backwards. Give reason.

A constant force of $15 \mathrm{N}$ acts on a body of mass $5 \mathrm{kg}$. Find the acceleration produced.

Why a cricketer lower his hands while catching a ball?

What is the amount of force required to a velocity of a car by $30 \mathrm{m} {\mathrm{s}}^{-1}$ starting from rest. It is given that the time taken is $10 \mathrm{s}$  and the mass of the car is $1000 \mathrm{kg}$.

The graph shows the retardation of a car of $1000 \mathrm{kg}$. Find the retarding force.    

A car moving with a speed of $72 \mathrm{km} {\mathrm{h}}^{-1}$ stops in $5 \mathrm{seconds}$ application of brakes. Assuming retardation to be uniform, find the retarding force. The mass of the car is $1000 \mathrm{kg}$.