How much work is done (physics)

Harry Potter (55kg) is on his magic broom and chasing the snitch at a constant velocity of 18 m/s straight up. He catches the snitch after going up 21 m. How much work did the broom do on Harry?

the amount of work is equal to his change in gravitational potential energy. In order to move upwards at any constant rate, a force needs to negate the force of gravity. that corresponds to work of m*g*h, 55kg*10 m/s^2* 21 m = 1.15 KJ

The answer is D 11KJ not 1.15KJ

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Here the work done is the change in potential energy as his kinetic energy ((mv^2)/2) will be constant

Potential energy = mg(change in h )

55*9.81*21 = 11320 j

These IS work done because he is moving in a Vertical direction so is doing work against gravity

W= force x displacement→force = mass x acceleration
w= MxAxD

If Harry moves at a constant velocity, he is not accelerating. Therefore, no work is being done.

Studying for finals? :)