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An aeroplane of mass 1.5 x 104 kg is moving at 60ms-1.

The pilot then revs up the engine so that the forward thrust of the propeller becomes 7.5 x 104 N. If the force of the air resistance has a magnitude

of 4.0 x 104 N, find the speed of the aeroplane after it has travelled 500m. Assume that the aeroplane is in level flight throughout this motion.

An archer pulls her bow string back 0.400m by exerting a force that increases uniformly from zero to 230N.

a) What is the equivalent spring constant of the bow?

b) How much work is done in pulling the bow?

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# Homework Help: Looking for Correct Answer

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