# Questions tagged [free-body-diagram]

A pictorial device which analyzes forces present on any body with the use of vectors. Allows easier grasping of problems involving either objects at equilibrium or in motion. Can be used to predict presence of forces.

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### Why friction of a wheel is zero? [duplicate]

MY physics teacher told us that friction is independent of surface area. but Also said that friction in a wheel is zero because the surface of wheel is in contact with wheel for only small amount of ...
1 vote
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### Does Newton's 3rd law hold true everytime? [duplicate]

Well,I know (and was also told) Newton's third law is just conservation of momentum in disguise. And momentum is only conserved in a system when $\sum F_{ext}=0$. Alright,suppose there is a system of ...
54 views

### How to calculate tension in this case? [closed]

I came up with this idea while learning rotational motion. Note: I have not found any question on it but its a concept I want to know. Take a rod of mass M and length L. Hang it with cealing using ...
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### Can a sand hill be modelled as an inclined plane? [closed]

I have modelled the sand pile as an incline plane that in in of itself im questioning whether is a right decision i was kinda confused will friction act up or down the incline on the grain of sand ...
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1 vote
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### Role of Friction in Pure Rolling

Consider a Sphere performing Pure Rolling on a rough surface.The velocity of centre of mass of sphere is towards right and it has a clockwise angular velocity,with acceleration of centre of mass a and ...
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### What is the relation between rope length, object weight and force needed?

Whenever I pull an object from a rope or cable, the weight never really feel the same depending on the rope length, and I would like to understand why, and learn more about the maths behind this. So, ...
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### I would like to calculate the lifting force required to stand up my motorcycle after laying it down on its side (real life scenario after a crash) [closed]

What would be the formula used to calculate the force required to lift a fallen motorcycle (assume a uniform mass...no lever effect) that weighs say 550 lbs? The answer is obviously angle-dependent......
103 views

### Two different versions of Newton's Third Law

I have two different versions of Newton's Third Law. Newton's Law is simply a way of describing forces. When a moving Object A, hits Object B and transfers all its energy to B, Object A stops because ...
31 views

### Equilibrium of a ladder kept leaning against a wall [closed]

If a ladder is kept leaning against a wall as in the picture, how to determine the direction of, i) The force exerted by the wall on the ladder? ii) The force exerted by the floor on the ladder? And ...
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### Is the person in the picture doing any work? [duplicate]

"In figure (i) the man walks 2m carrying a mass of 15kg on his hands. In figure (ii) he walks the same distance pulling the rope behind him. The rope goes over a pully and a mass of 15kg hangs at ...
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### Case study on inertia

When our upper body and lower body both are in contact with bus then after applying breaks why only upper body part moves forward?
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### How is mechanical energy conserved in inclined plane-block system?

This is a rather standard problem where there is an inclined plane (of mass M) on a frictionless horizontal surface and a block (of mass m) slides on it. The problem asks us to calculate the speeds of ...
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### Stacked block problem & static friction

For the two-block problem below, why is the static friction not equal to applied force when both blocks move with same acceleration? I mean that in physics it’s taught that static friction is always ...
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### Confusion in kinetic and static friction difference and approaching problems

Is the friction here kinetic since the blocks are moving down. I don't know how to know when to apply kinetic friction and when to apply static fricion. When motion is givien I understand and use ...
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