Question

A 2 kilogram rabbit starts from rest and is moving at 6m/s after 3 seconds. What net force must be exerted on the rabbit (by the ground) to cause this change in speed?

Answer 1

The best way to handle this is to apply Newton's
second law of motion:

Force = (mass) x (acceleration) .

But before we can do that, we need to figure out
the rabbit's acceleration.

Acceleration = (change in speed) / (time for the change)

= (6 m/s) / (3 sec)

= 2 m/s² .

Now we have both of the numbers we need in order to apply Newtons law:

Force = (mass) x (acceleration)

= (2 kg) x (2 m/s²)

= 4 kg-m/s² = 4 newtons .