# Challenging momentum questions!

I am finding trouble in the following qs, if someone can jus show me how to start off it will be very helpful. Plzz feedback any qs that are do able. Thnks.

1. A child in a boat throws a 5.40kg package out horizontally with a speed of 10m/s. Calculate the velocity of the boat immediately after, assuming it was initially at rest. Say the mass of the child is 26kg and the mass of the boat is 55kg.

2. A 1000kg Toyota collides with the rear end of a 2200kg Mercedes stopped at a red light. The bumpers lock, the brakes are locked, and the two cars skid forward 2.8m before stopping. The police officer, knowing that the coefficient of kinetic friction between the tires and the road is 0.40, calculates the speed of the Toyota at impact. What was the speed?

3. A softball of mass 0.220kg that is moving with a speed of 5.50m/s collides head on and elastically with another ball initially at rest. Afterwards it is found that the incoming ball has bounced backward with a speed of 3.7m/s. Calculate the mass of the target ball.

4. A distant solar system has a central star (akin to our Sun) that is currently "burning out". It is projected that the star will decrease in mass by 5% over the next 20 years. Over the same time interval, the star will shrink in radius by 12%. By what percentage will the stars escape velocity increase in the next 20 years.