You’re carrying a 4.0-m-long, 21 kg pole to a construction site when you decide to stop for a rest. You place one end of the pole on a fence

Question

You’re carrying a 4.0-m-long, 21 kg pole to a construction site when you decide to stop for a rest. You place one end of the pole on a fence post and hold the other end of the pole 35 cm from its tip. How much force must you exert to keep the pole motionless in a horizontal position?

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Khải Quang 5 years 2021-09-02T22:12:17+00:00 1 Answers 23 views 0

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  1. Philomena
    0
    2021-09-02T22:13:59+00:00
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    Answer:

    The weight of the pole can be assumed to act at the pole’s midpoint, which is 2m from the fence / pivot point, giving us a moment of 490Nm (245N x 2m).  We have to counteract this moment by holding the end of the pole.  So, we have a lever arm of 3.65m (4.0m – 0.35m), so we would need to exert a force of 134.4N (490N / 3.65m) at a point 35cm from the end of the pole.

    Explanation:

    happy to help:)

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