4) If an object of 40 kg is moving east at 20 m/s and collides with a 20 kg object moving along the same vector at 10 m/s, what will be the velocity of the smaller object if the larger object slows to 10 m/s?

The smaller object will move at 30 m/s

Explanation:

From the principle of conservation of linear momentum,

Momentum of objects before collision = momentum of objects after collision.

where are the masses  and velocities of the objects 1 and 2 respectively before collision.

Hence, the object will move at 30 m/s

Explanation:

In all collisions the total linear momentum of the system is conserved. Therefore:

So, represents the linear momentum before the collision and represents the linear momentum after the collision. Now, let:

According to the data provided by the problem:

Replacing the data into the linear momentum equation and solving for :

Thus, the velocity of the smaller object  after the collision is 30m/s