Calculating Rotational Force for a 5000kg Suspended Load

[rahim]

can someone help me?..

i have 5000kg suspended load..how do i calculate the force needed to rotate this load 90 deg. assuming perfect bearing?..thanks

 

[LostConjugate]

Any amount of force. Once it starts rotating it will not stop assuming perfect bearing. I wish I had a perfect bearing.

 

[sophiecentaur]

I wish I had a perfect bearing.

Go to deportment classes then. lol

 

[rahim]

im just saying friction is neglected..thanks

 

[mrspeedybob]

I was recently at a museum in Virginia that had a large stone globe in front of the building, I would estimate that it was 2 1/2 meters in diameter. The surface was very smooth and it was supported on a circular base. Water was forced up through the base which raised the globe slightly so that is was in physical contact with only water and air. While this in not a perfect bearing, it was a very good one. I could rotate the globe in any direction I wanted with 1 finger. The limiting factor for how fast I could accelerate the globe was not the strength of my finger but the lack of friction between my finger and the smooth, wet stone. Really I was only using about 1/4 of the strength of 1 finger. I inquired about the mass of the globe and was told that it weighs about 29 tons.

Here's a link to the museums website...
http://www.smv.org/exhibits.html
One of the photo's is of the globe I am describing.

 

[Drakkith]

im just saying friction is neglected..thanks

Any amount of force will eventually rotate it to 90 degrees. Similar to an object in space, the load will continue to move after any force is applied to it and then stopped. If you want to move it to 90 degrees in a specific timeframe, then that is different.

 

[dyce]

being an automotive technician, I would use an foot pounds torque wrench.

 

[Drakkith]

being an automotive technician, I would use an foot pounds torque wrench.

The OP is asking the question and telling us that there is no friction or anything, it is just a suspended load. ANY force will move it to 90 degrees as long as there is no resistance to the motion. In reality we would have to take friction and other effects into account.

 

[dyce]

The OP is asking the question and telling us that there is no friction or anything, it is just a suspended load. ANY force will move it to 90 degrees as long as there is no resistance to the motion. In reality we would have to take friction and other effects into account.

it would need to be falling or floating in space in order to get it to rotate with almost 0 force. but floating in water would be "close" to 0 friction. this is if it is a smooth object. so yea youre right. but to get it to rotate under strength of Earth's gravity pulling on it, there would always be resistance.

 

[Drakkith]

it would need to be falling or floating in space in order to get it to rotate with almost 0 force. but floating in water would be "close" to 0 friction. this is if it is a smooth object. so yea youre right. but to get it to rotate under strength of Earth's gravity pulling on it, there would always be resistance.

Which is why we were all talking about a situation with no resistance!