A sky-diver jumps from a stationary balloon. His initial downwards acceleration is 10m/s². Fig. 1.1 shows the directions of the air resistance and the weight of the sky-diver. [Figure 1.1] The mass of the sky-diver is 60kg and his weight is 600 N.

1. (a)Explain, using ideas about the forces, why his initial downwards acceleration is 10m/s².[2]
2. (b)When the parachute opens, the sky-diver experiences an upward acceleration for a short time. Explain why.[1]
3. (c)(i)Using Fig. 1.2, determine the terminal velocity of the sky-diver.[1]
4. (c)(ii)Calculate the resultant force on the sky-diver when his speed is 5.5m/s.[1]

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