Understanding Work in Physics: Force and Displacement Relationship

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In summary, the conversation discusses the calculation of work done by a force, with differing opinions on whether it is the scalar product of the force and potential displacement vector or the product of the force and resultant displacement. The teacher argues that the latter is the correct convention, while the speaker questions its logic and brings up the concept of conservative forces.
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Vykan12
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I've always thought that the work done by a force is the scalar product of the force vector and the potential displacement vector it would have if no other forces were acting on it. My teacher says that it is really the product of the force vector and the resultant displacement regardless of what other forces act on the system, and that you'd get the same net work with either calculation.

I don't see how the way he defines it would make any sense. For example, if you derive the work done by gravity, you could find it to be just about anything depending on the external forces in question, rather than just mg(y_1 - y_2). So what is the true convention?
 
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Hi Vykan12! :smile:

Work done by a particular force is (integral of) that force times the actual displacement (of the point of application of the force, if it's not a point body).

What the displacement would be if there were no other forces is irrelevant. :wink:
 
  • #3
Vykan12 said:
For example, if you derive the work done by gravity, you could find it to be just about anything depending on the external forces in question, rather than just mg(y_1 - y_2).
No, regardless of the path the object takes the work done by gravity will always be mg(y_1 - y_2).
 
  • #4
I can see that's where the properties of conservative forces come into play. Interesting.
 

FAQ: Understanding Work in Physics: Force and Displacement Relationship

What is work?

Work is the application of force to move an object over a distance. In other words, work is done when a force is applied to an object and the object is moved in the direction of the force.

What is the formula for calculating work?

The formula for calculating work is W = F * d, where W is work, F is the force applied, and d is the distance over which the force is applied.

What are the units of work?

The units of work are joules (J) in the metric system and foot-pounds (ft-lb) in the English system.

How is work related to energy?

Work is directly related to energy, as work is defined as the transfer of energy from one object to another by applying a force and causing the object to move. In other words, work is a means of transferring energy from one form to another.

What are some examples of work?

Some examples of work include lifting a book, pushing a car, and throwing a ball. Essentially, any time a force is applied to an object and the object is moved, work is being done.

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