How do you calculate joules necessary to rotate an object?

In summary, the individual is seeking to calculate the amount of energy required to rotate an object of 10kg and 1 meter in length from a diagonal downward position of 45 degrees to an upright position, considering only the force of gravity. The individual is unsure of the specific formula needed, but is considering using integration to account for the normal force.
  • #1
5P@N
58
3
NOTE: THIS IS NOT A HOMEWORK QUESTION!

I merely wish to know how to calculate the force necessary to rotate an object, say of 10 kg, from a certain downward diagonal direction of 45 degrees into an upright position considering only gravity.

I'll need to use some formula involving torque...
 
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  • #2
5P@N said:
NOTE: THIS IS NOT A HOMEWORK QUESTION!

I merely wish to know how to calculate the force necessary to rotate an object, say of 10 kg, from a certain downward diagonal direction of 45 degrees into an upright position considering only gravity.

I'll need to use some formula involving torque...
Your post is not clear.

In the title, it says you want to calculate joules necessary to rotate an object. In the OP, it says you want to calculate the force necessary.

Joules are the units of energy or work. Force is measured in units of Newtons.

What do you want to know?
 
  • #3
My bad. I've read the distinction between the two, but must have slipped.:rolleyes:
I want to know the energy, and so need to provide the dimension of the object: let's say it's 1 meter long.

I'm just making its characteristics up because I want to know the general approach that's necessary.

I'm thinking that I'll have to integrate sin all across its rotation to account for the normal force? Let's say the object starts at a diagonal downward position of 45 degrees.
 

1. How do you calculate the rotational kinetic energy of an object?

The rotational kinetic energy of an object can be calculated using the formula E = 1/2Iω^2, where E is the rotational kinetic energy, I is the moment of inertia, and ω is the angular velocity.

2. What is the difference between torque and work in rotational motion?

Torque is the measure of the force that causes an object to rotate, while work is the measure of the energy used to cause a change in the position or motion of an object. In rotational motion, torque is used to calculate the amount of work done on an object.

3. How do you calculate the moment of inertia of an object?

The moment of inertia of an object can be calculated by summing up the products of each particle's mass and its square distance from the axis of rotation. It can also be calculated using the formula I = mr^2, where m is the mass of the object and r is the distance from the axis of rotation.

4. Can you calculate the rotational kinetic energy of an object if you know its linear velocity?

Yes, the rotational kinetic energy of an object can be calculated using the formula E = 1/2Iω^2, where ω is the angular velocity. The linear velocity can be converted to angular velocity using the formula ω = v/r, where v is the linear velocity and r is the distance from the axis of rotation.

5. How do you calculate the work done on an object in rotational motion?

The work done on an object in rotational motion can be calculated using the formula W = τθ, where W is the work done, τ is the torque, and θ is the angle through which the object rotates. Alternatively, it can also be calculated using the formula W = ΔKE, where ΔKE is the change in rotational kinetic energy of the object.

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