# Homework Help: How to calculate required force to exert

1. Sep 9, 2009

### Moenieb.David

Hi,

I have a 5 kilogram weight that i want to move at a constant speed of 2m/s within a circle, thus the distance is negligible.
how do i calculate the force that is required to move the weight at that speed?

And yes, i am a beginner :-)

2. Sep 9, 2009

### Staff: Mentor

The centripetal force required is given by mv^2/r. What's the radius of the circle?

3. Sep 9, 2009

### Moenieb.David

hi,
Thanks for the response

4. Oct 25, 2010

### Selwyn

question seems incomplete
please mention the complete question :D

5. Oct 25, 2010

### Moenieb.David

Hi Selwys,

Thanks for the response, but what other info do you require?
What I wanted to know was how do I calculate the amount the FORCE required to move an object at a certain speed.
Lets say i wanna move a 5000 gram object at 2 metres per second along a: a straight line and b: in a circle. How much force do I need to apply to the object to get that type of movement speed for the object
Does this make sense?

6. Oct 25, 2010

### Moenieb.David

Hi Selwys,

Thanks for the response, but what other info do you require?
What I wanted to know was how do I calculate the amount the FORCE required to move an object at a certain speed.
Lets say i wanna move a 5000 gram object at 2 metres per second along a: a straight line and b: in a circle. How much force do I need to apply to the object to get that type of movement speed for the object
Does this make sense?

7. Oct 25, 2010

### Staff: Mentor

Sorry, I must have missed this post. In any case, the centripetal force required is given by the formula in my earlier post.
No net force is required to move an object in a straight line at constant speed. (Consider Newton's First Law.) Of course, if friction or other forces are involved you'll have to overcome them.

To make something move in a circle requires a net centripetal ('toward the center') force.

8. Oct 25, 2010

### Selwyn

ah sorry sorry :D
i didnt really read the question
yeah the force applied can be given by m*v^2/r
well u should call it velocity since this speed has direction
nevermind.....