16. Exercises

A car, of mass 1000 kg, is travelling at 20 \displaystyle \text{m}{{\text{s}}^{-1}}, when it drives into a truck, of mass 4000 kg, which was moving at 10 \displaystyle \text{m}{{\text{s}}^{-1}} in the same direction. After the collision the two vehicles move together. Find the speed of the vehicles after the collision.

A child of mass 40 kg stands on a skate board, of mass 2 kg. Initially both are at rest. The boy jumps off so that he travels horizontally at 3 \displaystyle \text{m}{{\text{s}}^{-1}}. Find the speed of the skateboard.

Two particles travel towards each other along a straight line. One has mass 3 kg and speed 4 ms-1. The other has mass 5kg and speed 2 \displaystyle \text{m}{{\text{s}}^{-1}}. When they collide the 3kg mass is brought to rest. What happens to the 5kg mass ?

A toy train, of mass 200 grams, is moving along a straight track at 1.8 \displaystyle \text{m}{{\text{s}}^{-1}}, when it collides with a stationary truck of mass, of mass 300 grams, during the collision the trucks are coupled together. Find the speed of the truck after the collision.

Two particles are travelling towards each other when they collide. One has mass 2kg and was travelling at 5 \displaystyle \text{m}{{\text{s}}^{-1}} before the collision and the other has mass 3 kg and a velocity of 6 \displaystyle \text{m}{{\text{s}}^{-1}} before the collision. The 2kg mass changes direction and moves at 2 \displaystyle \text{m}{{\text{s}}^{-1}} after the collision. Describe how the 3kg mass moves after the collision.

Two particles A and B, have masses 2 kg and 3kg respectively. Before a collision between the two particles, they have velocities (\displaystyle 9\mathbf{i}+5\mathbf{j}) \displaystyle \text{m}{{\text{s}}^{-1}} and (\displaystyle -3\mathbf{i}+4\mathbf{j}) \displaystyle \text{m}{{\text{s}}^{-1}} respectively, where \displaystyle \mathbf{i} and \displaystyle \mathbf{j} are perpendicular unit vectors. During the collision the two particles coalesce and move together after the collision.

Find the velocity of the particles after the collision.