A trolley of mass 0.20 kg is at rest on a frictionless surface. A block of wood is attached to the trolley. The volume of the block of wood is 0.0012m³, and the density of the wood is 650kg/m³.

1. (a)Calculate the combined mass of the trolley and block. combined mass = ................................................................. kg [2][2]
2. (b)Fig. 1.1 shows that a student attaches a spring of spring constant 14N/m to the front of the trolley. [Figure 1.1] The student holds the trolley and block and stretches the spring. He releases the trolley and block. The trolley and block accelerate from rest. As the trolley and block accelerate, the student keeps the extension of the spring at 0.035 m.
3. (b)(i)Calculate the force exerted by the spring on the trolley. force = ................................................................. N [2][2]
4. (b)(ii)The trolley and block are pulled a distance of 0.86 m by the spring. Calculate the work done on the trolley. work done = ................................................................. J [2][2]
5. (b)(iii)Explain why the power transferred to the trolley and block increases as the speed increases.[2]

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