# Torque and Force exerts on pulley

1. Nov 12, 2007

### saturn67

A 12.0 kg box resting on a horizontal, frictionless surface is attached to a 5.00 kg weight by a thin, light wire that passes over a frictionless pulley. The pulley has the shape of a uniform solid disk of mass 1.80 kg and diameter 0.520 m.

i found
horizontal tension = 32.8N

vertical tension = 35.3N

After the system is released, find magnitude of the horizontal and vertical components of the force that the axle exerts on the pulley.?

i think Fx = 32.8
but Fy = 35.3+mg i think my Fy is wrong

Can someone help me out?

2. Nov 12, 2007

### saturn67

anyone got any idea?

Fx,Fy of that answer is wrong .. :(

i think Fx of my right

3. Nov 12, 2007

### saturn67

can anyone help me please? =(

4. Nov 13, 2007

### catkin

The solution will need to take account of the rotational dynamics of the pulley.

5. Nov 13, 2007

### saturn67

can u give me more detail on it? i still little confuse

6. Nov 13, 2007

### catkin

Is that the full, original text of the question?

Three masses will accelerate together in response to the weight of the hanging mass. One of them, the pulley, will accelerate rotationally. Because both masses and the edge of the wheel are connected by the wire we know that all of them accelerate at the same weight (we are not told anything about the wire's elasticity so have to presume it is linearly stiff).

Once we find that acceleration we can find the tension in the vertical and horizontal parts of the wire.

Prudent now to draw a free body diagram of the pulley. Whatever the resultant of the forces acting on the pulley, the axle is opposing.