Angular acceleration and Torque when rod reaches vertical position?

In summary, the rod has a mass of 1.30 kg and a length of 0.670 m. When released from rest in the horizontal position, the torque is 4.27 N*m and the angular acceleration is 21.9 rad/s^2. When the rod reaches the vertical position, the torque and angular acceleration are both 0, as the moment arm of the weight force is 0 and there is no rotation.
  • #1
sweetpete28
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Angular acceleration and Torque when rod reaches vertical position??

A rod (mass 1.30 kg, length .670 m) attached to a frictionless axis is released from rest in the horizontal position. What is the magnitude of the torque and angular acceleration when the rod has reached the vertical position?

I know at horizontal position (immediately after release) Torque = FR = mg(L/2)= 4.27n-m and torque = I∂ giving ∂ = 21.9 rad/s^2...but how do I solve for when it hits vertical position...? Please help!
 
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  • #2


When the rod is hanging vertically, what is the moment arm of the weight force about the pivot?
 
  • #3


Is it 0 b/c it is through the axis of rotation?
 
  • #4


Yes, correct. So what's the torque and angular acceleration at this position?
 
  • #5


Both would be 0 then, right?
 
  • #6


sweetpete28 said:
Both would be 0 then, right?

Right!
 

1. What is angular acceleration?

Angular acceleration is the rate of change of angular velocity. It is the measure of how quickly an object's angular velocity is changing over time.

2. How is angular acceleration calculated?

Angular acceleration can be calculated by dividing the change in angular velocity by the change in time. It is represented by the symbol alpha (α) and has units of radians per second squared (rad/s²).

3. What is torque?

Torque is the measure of the force that causes an object to rotate about an axis. It is the product of the force applied and the distance from the axis of rotation. It is represented by the symbol tau (τ) and has units of newton-meters (Nm).

4. How does torque affect angular acceleration?

Torque and angular acceleration are directly proportional. This means that the greater the torque applied to an object, the greater the resulting angular acceleration will be. This can be seen in the equation α = τ/I, where I is the moment of inertia of the object.

5. What happens to angular acceleration when a rod reaches a vertical position?

When a rod reaches a vertical position, its angular acceleration decreases and eventually becomes zero. This is because the torque exerted by gravity on the rod is also zero at this position, resulting in no change in angular velocity. This is known as the equilibrium position.

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