# Physics question

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#1
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#2
I need to know the weight W of the ladder
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1 month ago
#3
Since it is stationary the forces in any given direction have to add up to zero (Newton’s first law). If you resolve the forces vertically, the 100N force upwards from the floor must add to the weight force to equal zero.

100N + W = 0
So W = -100N (or 100N if you just want the magnitude)
Last edited by jasminelr; 1 month ago
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#4
(Original post by jasminelr)
Since it is stationary the forces in any given direction have to add up to zero (Newton’s first law). If you resolve the forces vertically, the 100N force upwards from the floor must add to the weight force to equal zero.

100N + W = 0
So W = -100N (or 100N if you just want the magnitude)
Thank you, is the 30N useless then? I thought if the ruler was exerting a force on the wall, the force acting on the floor would be less than the weight? Why isn’t this the case?
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1 month ago
#5
(Original post by gymjam)
Thank you, is the 30N useless then? I thought if the ruler was exerting a force on the wall, the force acting on the floor would be less than the weight? Why isn’t this the case?
The force on the wall and the friction force that you drew on in the first part of the question balance each other out (they are both 30 but in opposite directions). If you were to increase the weight of the ladder, the force the ladder exerted on the wall would increase, but so would the friction force from the ground (assuming the ladder didn’t move) meaning these two would still cancel out and the two vertical forces would still be equal to one another.
Last edited by jasminelr; 1 month ago
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