Set 4 Problem number 6

• Problem

• Solution

• Generalized Solution

Problem

The momentum of an object of mass 14 kg is known to be -42 kg m/s.

What is the velocity of this object?

Solution

Momentum is the product of mass and velocity.

It follows that if momentum and mass are known, velocity is momentum / mass.

• Dividing -42 kg m/s by 14 kg, we obtain the velocity

• v = -42 kg m/s / ( 14 kg) = -3 m/s.

Generalized Solution

Momentum p is the quantity that changes with impulse, the product mv of mass and velocity:

• p = m * v

Thus we easily find the velocity of an object of known mass if we know its momentum:

• v = p / m.