Dynamics

Pulleys

AP Free Body Diagrams

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Finding the Acceleration

Assuming a frictionless, massless pulley, ... determine the acceleration of the block after the large block is released.

Atwood machine free-body diagram: mass M and mass m connected over a pulley
Two blocks, M and m, connected by a rope over the pulley
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Let's make clockwise positive

Fnet = ma

[Mg − mg] = (M + m)a

g(M − m) (m + M) = a

Only applies when surface frictionless

Finish This Sentence

According to Newton's 2nd Law the acceleration of the 2 masses comes from weight difference and…..

Atwood machine free-body diagram: mass M and mass m connected over a pulley

Tension in the Rope

Force of tension of the rope on mass m, M?

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Atwood machine free-body diagram: mass M and mass m connected over a pulley

Rule — One Rope, One Tension

Let's Make Clockwise Positive

Atwood machine free-body diagram: mass M and mass m connected over a pulley

ΣFy = Ma

Mg − Tf = Ma

Tf = Mg − Ma

Interactive Pulley Simulation

Full Screen

Pulley / Table