Understanding Work - High School Physics
Card 0 of 7
A bodybuilder lifts a 
weight upward 
, and then returns it to its original position, all with a constant speed. What is the net work done on the weight?
A bodybuilder lifts a
Work is a vector quantity equal to the change in energy in a given direction. Our net work will be equal to product of force and displacement.
We can write this equation in terms of Newton's second law to incorporate our given values.
During its motion the weight travels a distance of 
upward, and then 
downward. Its total distance will be 
, however, we are looking for its displacement. The initial height and final height are equal, making the displacement equal to zero.
The total work will be zero because there was no net displacement.
Work is a vector quantity equal to the change in energy in a given direction. Our net work will be equal to product of force and displacement.
We can write this equation in terms of Newton's second law to incorporate our given values.
During its motion the weight travels a distance of
The total work will be zero because there was no net displacement.
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A 
crate slides along the floor for 
. What other piece of information do we need to find the work done?
A
The formula for work is 
, or work equals force times distance.
Since 
, you can expand the work formula a little bit to see 
.
The problem gives us the mass and the distance traveled, but not the acceleration. Given the acceleration, along with the mass and distance, we would be able to calculate the work.
The formula for work is
Since
The problem gives us the mass and the distance traveled, but not the acceleration. Given the acceleration, along with the mass and distance, we would be able to calculate the work.
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Miguel pushes a crate with 
of force. What other piece of information do we need to find the work he does?
Miguel pushes a crate with
The formula for work is 
, or work equals force times distance.
The problem gives us the mass, but is missing the distance. Given the distance, we would be able to calculate the work.
The formula for work is
The problem gives us the mass, but is missing the distance. Given the distance, we would be able to calculate the work.
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Which of the following is an example of work?
Which of the following is an example of work?
Work is a force times a distance or 
.
Only one of these has a force times a distance: the weightlifter lifting a weight above his head.
The car moving at a constant velocity has no acceleration and therefore no force.
Typing essays does not require a force times a distance (though it sure feels like work!).
If the skier has no loss in energy, then no work was done, as work is also the measurement of the change in energy.
The man sitting in a chair has a constant velocity of zero, no acceleration, and therefore no force.
Work is a force times a distance or
Only one of these has a force times a distance: the weightlifter lifting a weight above his head.
The car moving at a constant velocity has no acceleration and therefore no force.
Typing essays does not require a force times a distance (though it sure feels like work!).
If the skier has no loss in energy, then no work was done, as work is also the measurement of the change in energy.
The man sitting in a chair has a constant velocity of zero, no acceleration, and therefore no force.
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Which of these is a correct formula for work?
Which of these is a correct formula for work?
Work is produced when a force is used to create a change in distance. The amount of work is given by the product of the distance traveled and the force applied.
Work is produced when a force is used to create a change in distance. The amount of work is given by the product of the distance traveled and the force applied.
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Michael pushes a box 
across the floor. If the box moves with a constant velocity, what is the total work done?
Michael pushes a box
Works is equal to force times distance:
Since the box moves with a constant velocity, it has no acceleration. Remember that 
, so if there is no acceleration, then there must be no net force.
If there is no net force, then there is also no work.
Works is equal to force times distance:
Since the box moves with a constant velocity, it has no acceleration. Remember that
If there is no net force, then there is also no work.
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Rodrigo pushes a sofa 
down a long hallway. If the couch moves with a constant velocity, how much work does Rodrigo do?
Rodrigo pushes a sofa
Work is the product of a net force over a given distance.
In order for there to be work, there must be a net force applied and the object must have a non-zero displacement. In this question we are given the displacement, but we have to solve for the force.
The question only tells us that the couch moves with constant velocity. This tells us that acceleration is zero. If acceleration is zero, then force must also be zero according to Newton's second law.
If the force is zero, then the work is also zero.
Work is the product of a net force over a given distance.
In order for there to be work, there must be a net force applied and the object must have a non-zero displacement. In this question we are given the displacement, but we have to solve for the force.
The question only tells us that the couch moves with constant velocity. This tells us that acceleration is zero. If acceleration is zero, then force must also be zero according to Newton's second law.
If the force is zero, then the work is also zero.
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