# Rotational Motion around a Fixed Axis

• shaka23h
In summary, the conversation discusses two problems involving a beam and a pulley. The first problem involves finding the tension in a cable supporting a beam and the components of the force exerted by a wall on the beam. The second problem involves finding the angular acceleration of a pulley and the tension in a cord wrapped around it. The conversation also suggests using the search function to find examples of expressing equilibrium.
shaka23h
Hi, I'm really confused about these 2 problems to the extent that I have no idea where to start.

Any kind of suggestions and hints would be really appreciated.

Thanks

A 1090-N uniform beam is attached to a vertical wall at one end and is supported by a cable at the other end. A 1960-N crate hangs from the far end of the beam. Using the data shown in the figure, find (a) the magnitude of the tension in the wire and the magnitudes of the (b) horizontal and (c) vertical components of the force that the wall exerts on the left end of the beam.

http://edugen.wiley.com/edugen/courses/crs1507/art/qb/qu/c09/ch09p_20.gif

A block (mass = 1.4 kg) is hanging from a massless cord that is wrapped around a pulley (moment of inertia = 1.3 x 10-3 kg·m2), as the figure shows. Initially the pulley is prevented from rotating and the block is stationary. Then, the pulley is allowed to rotate as the block falls. The cord does not slip relative to the pulley as the block falls. Assume that the radius of the cord around the pulley remains constant at a value of 0.049 m during the block's descent. Find (a) the angular acceleration of the pulley and (b) the tension in the cord.

http://edugen.wiley.com/edugen/courses/crs1507/art/qb/qu/c09/ch09p_40.gif

Regarding the first problem, do you know how to express equilibrium?

Regarding the first problem, do you know how to express equilibrium?

hmm not exactly,

I guess I'll read over the chapter again and see.

Do so. And if you're still unsure after that, you can use the search button with words like 'static, equilibrium', etc. to see some examples.

## 1. What is rotational motion around a fixed axis?

Rotational motion around a fixed axis is when an object rotates around a fixed point or axis. This type of motion is different from linear motion, where an object moves in a straight line.

## 2. What factors affect rotational motion?

The factors that affect rotational motion around a fixed axis include the mass of the object, the distance from the axis of rotation, and the applied torque or force.

## 3. How is rotational motion calculated?

The rotational motion of an object can be calculated using the equation τ = Iα, where τ is the torque applied, I is the moment of inertia, and α is the angular acceleration.

## 4. What is the difference between angular velocity and linear velocity?

Angular velocity is a measure of how fast an object is rotating around an axis, while linear velocity is a measure of how fast an object is moving in a straight line. Angular velocity is measured in radians per second, while linear velocity is measured in meters per second.

## 5. How does rotational motion affect an object's stability?

The stability of an object is affected by its center of mass and its moment of inertia, which are both influenced by rotational motion. An object with a lower center of mass and a smaller moment of inertia will be more stable in rotational motion.

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