Rotational Motion- Pulleys with Friction

In summary, the problem involves two masses suspended from a pulley with a mass of 0.20kg and a radius of 0.15m. The pulley has a constant torque of 0.35 MN due to friction between the pulley and its axle. The question asks for the magnitude of acceleration of the suspended masses (m1=0.4kg and m2=0.8kg), neglecting the mass of the string. The relevant equations are T1=M1g-M1a and T2=M2g+M2a, where T1 and T2 are the tensions of the cords, M1 and M2 are the masses of the suspended masses, and g is the acceleration due to
  • #1
danield
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Homework Statement


Two Masses are suspended from a pulley. The pulley itself has a mas of .20kg a radius of .15m a constant torque of .35 MN due to the friction between the rotating pulley and its axle. What is the magnitude of the acceleration of the suspended masses if m1= .4kg and m2= .8 kg (neglect the mass of the string)
Pulley
| |
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M2 M1




Homework Equations


T1= M1G - M1A
T2= M2G + M2A
Torque= FL = Moment of Inertia x Alpha,
I= 1/2 mr^2

The Attempt at a Solution


I have tried solving this by solving for A when T2-T1= I alpha, but i really don't know how to apply the fact that the tension is different of both cords due to the friction on the pulley I am stuck...
 

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  • #2
I have tried everything... but still i can't get to the answer.. i get to the formula a=(m2-m1)g/(1/2M+m1+m2) but after that i don't know how to apply the torque... :( need help
 
Last edited:
  • #3
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FAQ: Rotational Motion- Pulleys with Friction

What is rotational motion?

Rotational motion is the movement of an object in a circular or curved path around a fixed point, known as the axis of rotation.

How do pulleys affect rotational motion?

Pulleys are used to change the direction of a force and can either increase or decrease the amount of force needed to move an object. In rotational motion, pulleys can change the direction of torque, which is the force that causes an object to rotate around an axis.

What is friction in rotational motion?

Friction is the resistance force that occurs when two surfaces come in contact with each other. In rotational motion, friction occurs between the pulley and the string or belt that is in contact with it. This friction can cause a decrease in the efficiency of the pulley system.

How does friction affect pulleys in rotational motion?

Friction can cause a decrease in the efficiency of the pulley system by creating a resistance force that opposes the motion of the pulley. This can result in a loss of energy and can also affect the accuracy of the motion.

How can we reduce friction in pulleys during rotational motion?

There are a few ways to reduce friction in pulleys during rotational motion. One way is to use lubricants, such as oil or grease, to reduce the friction between the pulley and the string or belt. Another way is to use ball bearings or roller bearings in the pulley system, which can reduce the contact surface area and therefore reduce friction. Additionally, using materials with low coefficients of friction, such as Teflon or graphite, can also help to reduce friction in pulleys.

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