Alex asked in Science & MathematicsPhysics · 1 month ago

What was the work done against air friction?

A 10kg rock is dropped from rest and falls vertically for 5.0s. After this time the rock was moving at 49m/s. What was the work done against air friction in this time?

Update:

Sorry it was meant to be moving at 40m/s

1 Answer

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  • 1 month ago

    weight is 98 N

    downward force is 98 N – force of air friction (call it f)

    downward acceleration is F/m = (98 – f)/10 = 9.8 – f/10

    acc = ΔV/Δt = 49/5 = 9.8 m/s = 9.8 – f/10

    f (force of friction) = 0

    work against air resistance = 0

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