A jet ski is a type of boat that carries one or two people and travels at high speed on water. Fig. 1.1 shows a student riding on a jet ski. [Figure 1.1] A high-speed jet of water is forced backwards out of the back of the jet ski by a pump inside the jet ski.

1. (a)(i)The pump increases the momentum of the water that is forced backwards out of the back of the jet ski. Complete the word equation to show the relationship between the resultant force on an object and the change in momentum of the object. resultant force =[1]
2. (a)(ii)In 2.0s, the pump increases the backwards speed of 180 kg of water by 30 m/s. Calculate the backwards force exerted on the water. force = ........................................................... N[2]
3. (b)(i)Using Newton's third law of motion, explain why there is a forwards force on the jet ski.[2]
4. (b)(ii)The student has a mass of 70 kg and the jet ski has a mass of 280 kg. Use your answer from (a)(ii) to determine the acceleration of the student and jet ski when no resistive forces are acting. acceleration = ................................................. m/s²[2]
5. (c)The jet ski reaches a speed of 20 m/s. Calculate the total kinetic energy of the student and jet ski at this speed. kinetic energy = ................................................... J[3]

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