# Two boxes connected to a string over an ideal pulley?

## Homework Statement

Two blocks are connected by a string that goes over an ideal pulley as shown in the figure and pulls on block A parallel to the surface of the plane. Block A has a mass of 3.00 kg and can slide along a rough plane inclined 30.0° to the horizontal. The coefficient of static friction between block A and the plane is 0.400. What mass should block B have in order to start block A sliding up the plane?

## Homework Equations

box A- sum of x & sum of y
box B- sum of y
plug into each other

## The Attempt at a Solution

m2=(ms*m1*sin(theta)+m1*cos(theta)
=3.198

Thanks.

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First of all. What are all the forces acting upon block A?

First of all. What are all the forces acting upon block A?
The forces acting on block A are static friction, fnormal, gravity, and ftension.

Yes. So the friction force and force of gravity are preventing the block from sliding up the ramp. What's next?

Yes. So the friction force and force of gravity are preventing the block from sliding up the ramp. What's next?
ffriction = -.4*9.81*3
fgrav= -sin30*9.81*3
ftension =m*9.81

ffriction +fgrav = ftension

Not sure which part i messed up

Last edited:
ffriction = -.4*9.81*3
Friction force is equal to μF$_{normal}$.