Examples in which force is exerted on an object without doing work

In summary: If you then pull your hand away from the wall, you have exerted a force on the wall, and that force has done work on the wall, because the wall has moved.
  • #1
Faiza
96
0
Q.Give two examples in which force is exerted on an object without doing any work on the object.

ummm i can't think of any example, i think the upward force does not cause the horizontal displacement so this is a NON-example of work?
 
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  • #2
I'm sure you know how "work" is defined. If the force isn't zero, then something else has to be (in order to make the work zero). What is that other thing? If you understand that, I don't think you will find it difficult to think of two, or even two hundred, examples.
 
  • #3
work is force and displacement in the same direction so
 
  • #4
example

force of gravity? cud that be one
 
  • #5
Any time a force is exerted but the object is not displaced in a direction parallel to the force, work is not done.

Force of tension on a ball rotating on the end of a string.

Normal force and gravitational force on an object at rest or moving across a level floor.
 
  • #6
Faiza u r close but not close enough!

Work is defined as dot product of Force vector f and displacement vector s.
W = f.s = fscos(theta)
where theta is the angle between f and s.
if this theta is pi/2 then cos(pi/2)=0 hence W = 0

if f is perpendicular to s then W = 0.

-- AI
 
  • #7
ohh okay...i get it
 
  • #8
Thanksss!
 
  • #9
any other examples?
 
  • #10
Any force that doesn't move the object is a good example. Suppose e.g. that you're standing still on a slope. There are three forces acting on you, but none of them is doing any work, so you have three good examples right there.
 
  • #11
Go stand next to a solid wall and push on the wall as hard as you can...assuming the wall does not move...then you did no work on it.
 

1. How can force be exerted on an object without doing work?

Force can be exerted on an object without doing work when the object does not move in the direction of the force, or when the force is perpendicular to the displacement of the object.

2. Can you give an example of force being exerted without doing work?

Yes, an example of this is a person holding a heavy book above their head. The force of gravity is acting on the book, but since the person is not moving the book, no work is being done.

3. What is the difference between force and work?

Force is a push or pull on an object, while work is the result of applying a force to an object and causing it to move in the direction of the force.

4. Is energy always involved when force is exerted on an object?

No, energy is not always involved when force is exerted on an object. This is because work, which is the transfer of energy, only occurs when the object moves in the direction of the force.

5. How is the concept of force without work important in physics?

The concept of force without work is important in physics because it helps us to understand the relationship between force, work, and energy. It also helps us to differentiate between different types of forces and their effects on objects.

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