A railway truck of mass 20,000 kg is moving at a speed of 4.5 ms". It catches up and collides with a loaded truck of total mass 60,000 kg which is moving in the same direction at 1.5 ms spring buffers 20 000 kg 60 000 kg 45 ms 15 mad The graph below shows the speed of the trucks before, during and after the collision. The heavier truck is plotted In black and the speed of the lighter truck in red, Speed /mall2.0 10- 0.10 8 Time / s ") By means of a calculation, determine the speed of the lighter truck after the collision. (3 marks) bj Calculate the force that each truck exerts on the other. (4 marks) cj ij calculate the kinetic energy in total for both trucks when they are in contact during the collision. (3 marks] W| Calculate the total Kinetic energy after the collision (3 Marks) Illj Suggest a reason for any difference between these kinetic energies. (1 mark]