Pendulum work?

A simple pendulum, consisting of a mass m tied to an inextensible mass rope

negligible and length L, oscillates in such a way that when the mass is at its maximum

height the rope forms an angle of 10 ° with the vertical. Calculate the work done:

A) by weight force when the pendulum moves from the highest to the lowest point AND VICEVERSA

I know that the answer is mgL(1-cos10) but I don't understand the sign. Is it +mgL(1-cos10) or mgL(1-cos10)?

Update:

or - mgL(1-cos10)? 

2 Answers

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  • Whome
    Lv 7
    1 month ago
    Favorite Answer

    Work is positive when the force direction and the movement direction are identical. 

    As "down" is associated with the direction of gravity and weight, gravity does positive work when the mass is falling. "AND VICEVERSA"

    • stella1 month agoReport

      thank u

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  • 1 month ago

    work done by the weight moving down is positive. 

    work done by the weight moving up is negative. 

    • stella1 month agoReport

      thank u

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