Rotation

# Why work done by centripetal force during half rotation is zero?

###### Wiki User

###### August 10, 2013 1:49PM

work done is zero because force is toward the centre and distance is tangent to the circle so cos90 is equal to zero.[abbasia]

## Related Questions

###### Asked in Cars & Vehicles

### Why does work done by centripetal force is zero?

An object moves in a circle at constant speed. The work done by
the centripetal force
is zero because:
1. the displacement for each revolution is zero
2. the average force for each revolution is zero
3. there is no friction
4. the magnitude of the acceleration is zero
5. the centripetal force is perpendicular to the velocity

###### Asked in Physics

### Why is the work done by centripetal force is zero?

Take the example of a satellite moving around the earth:
In this case, the satellite is moving in a circular path and the
centripetal force is provided by the gravitational force of the
earth. At every point in the circular path, the centripetal force
acts at right angles to the direction of motion of the satellite,
i.e. the force and displacement are perpendicular to each
other.
therefore Ɵ = 90 0
W= Fs cos Ɵ
= Fs cos 900
= Fs 0
=0

###### Asked in Science

### When body moves in a circular path how much work is done by the body?

Zero.
This is because when a body when around in a circle, a
centripetal force acts on the particle to keep it at that fixed
distance from the centre. At each point, the force and the
displacement are perpendicular to each other. Hence no work is
done.
The answer is NOT Zero! A Force is required in the direction of
motion around the circle. At every point (an infinite number of
them) there must be a Force PERPENDICULAR to the Centrifugal and
Centripetal Forces or the object would not move. Therefore the
amount of work done is the product of that FORCE times the
circumference of the circular path, if only considering one
revolution.

###### Asked in Science

### What is the evidence for determining whether or not work is done on an object?

Basically if the energy of the object has changed.
For example if you lift something off the ground you have
applied a force through a distance in the same direction as the
force. By lifting the box you have given it gravitational potential
energy (mgh). If you drop the box then gravity does work because
the force of gravity will apply a force through a distance in the
same direction.
Just because there is force, doesn't mean work has been done.
For example if you look at uniform circle motion even though there
is a force, known as centripetal force, there is no work being
done. This is because centripetal force is always perpendicular to
velocity and only components of force parallel to the object can do
work on it. We can tell no work has been done because the kinetic
energy of the object remains the same (=1/2*m*v2).

###### Asked in Science

### Torque and work is a product of force and distance.Yet torque and work are different.What is it about the distances that makes the torque and work different?

Torque describes a rotational force, caused by a
force acting at right-angles to the radius of rotation. To measure
torque, we multiply the force, in newtons, by the radius of
rotation in metres -so, torque is measured in newton metres
(N.m).
Work is measured by multiplying the force on an object by
the distance through which it moves, and is measured in joules
(J).
The work done by force of torque (not by torque) is determined
by multiplying the force, not by the radius of rotation, but by the
distance the force acts around the circumference of
rotation. So, if torque causes a complete rotation, then the
work done by that torque will be the force times (2 pi r).
One joule is equal to one newton-meter. It is a measure of work
or energy.
Torque can be expressed in joules (J), but they really mean
joules per radian. They're talking about the amount of work this
torque is capable of doing for each radian of rotation. When using
radian measure mention of radian is often left out, as in this
case.

###### Asked in Cars & Vehicles

### Work done by centripetal force?

Some work done by centrifugal force is present in our everyday
lives. For instance, a clothes washer uses a rapidly spinning drum
to sling and squeeze the water and soap out of clothes to wring
them out. Another example is a carnival ride, such as one with
hanging swings on it. As the ride spins faster, the swings swing
outward due to centrifugal force!

###### Asked in Physics

### Example of force that moves but does no work?

work = force . distance.
Since Force and distance are both vectors (work is the dot
product), when the net distance = 0 (back to the point of origin),
work = 0. That is, if the force is such that it moves the object
back to the point of origin, it has done zero work.
A centripetal force is one example. The distance = 0 when the
object finishes one complete revolution. No work has been done
since the beginning of the revolution.

###### Asked in Physics

### What is about distance that make the torque and work different?

What the hell you talkin 'bout?
Ignoring the previous answer...
For torque, 'distance' refers to the radius of rotation. For
work, 'distance' refers to the distance travelled in the direction
of a force. To find the amount of work done by torque, multiply the
force by the distance travelled around the circumference of
rotation.

###### Asked in Physics, Chemistry

### What is the work done by an electron revolving in a circular orbit of rdius r around the nucleus?

Here a centripetal force provided by electrostatic force of
attraction acts
on the electron towards the centre of orbit but motion is along
the tangent to
the circular orbit at ecah point. As force and displacement are
in mutually
perpendicular directions at each point, the work done is
zero.
E V SHAKKEER HUSSAIN

###### Asked in Physics

### What are the conditions of zero work?

Hello word performed is got by the expression F s cos@
If F ie force is not applied at all then no work could be
performed.
If s ie displacement is zero then work is not done thought force
is acting
Thirdly if @ is 90 deg, ie the angle between the force applied
and displacement made is 90 deg, then no work is said to be done by
the force. This is the case the work performed by centripetal force
on a rotating body.

###### Asked in Physics

### How is artificial gravity provided by the centripetal force?

In science-fiction novels, large wheels are set up in space. It
is very likely that this will eventually be done seriously.
Somebody on the rim of such a large wheel would be accelerated
towards the center of the wheel; the acceleration has a magnitude
of v2/r. The person or object would feel this as a centrifugal
force - a ficticious force. On a small scale, this force has just
the same effect as gravitation.