Anonymous
Anonymous asked in Science & MathematicsPhysics · 8 years ago

physics question on finding the distance?

Zack pushes Jenny with a force of 125N over a distance 1m. How far would Jenny slide across the floor after Zack's push ends? Jenny's mass = 20kg

(coefficient of kinetic friction between Jenny's feet and the floor = 0.25)

There's frictional force acting on Jenny when Zack pushes her and she slides on her own after Zack's push.

How would you do this question? Please explain step by step. The answer is 1.55m. Thank you!

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  • 8 years ago
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    Jenny's mass is 20kg.

    (20 x 9.8) = 196N. normal force on floor.

    Kinetic friction force = (196 x 0.25) = 49N.

    Zack's net applied force = (125N - 49N) = 76N.

    Jenny's acceleration = (f/m) = 76/20, = 3.8m/sec^2.

    Jenny's velocity after 1 metre push = sqrt.(2a x 1) = 2.757m/sec.

    Jenny's braking force = 49N.

    Braking acceleration = (f/m) = 49/20, = - 2.45m/sec^2.

    Distance to stop = (v^2/2a) = (2.757^2/4.9) = 1.55 metres.

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