Help finding the work done given 3 different distances?

In summary, the student did work by lifting the book from the ground to a height of 1.25m, but the weight force did not do any work when the book was moved horizontally to a shelf at a distance of 8.0m. The correct calculation for the work done by the student is 0.95 N * 0.75 m = 0.71 J. The student's attempt at a solution is incorrect as it does not take into account the angle between the force and displacement, and the displacement for the second lift is not 2.0m.
  • #1
fixedglare
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Homework Statement



a student lifts a book of 0.95 N to a height of 1.25 m. Then the student carries the book to a shelf at a distance of 8.0 m and places it at a height of 2.0 m. How much work did the student realize over the book?

Homework Equations


W = Fd


The Attempt at a Solution



.95 N * 1.25 m + .95 N * 2.0 m + .95 N * 8.0 m = 1.2 + 1.9 + 7.6 = 10.7 J

Is this correct?
 
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  • #2
No, since the only force in question here is weight force, and it doesn't do work at every displacement in the problem. It does for the lift from ground to 1.25m, but across the distance of 8.0m, does the force do any work? Think about the equation:
$$W = Fdcos\theta$$
Also, for the lift to 2.0m, you're misinterpreting the displacement. It says it's lifted to a height of 2.0m, not that the displacement is 2.0m. It starts at a height of 1.25m (from the first part), and then it's moved from there to 2.0m.
 

Related to Help finding the work done given 3 different distances?

1. How do you calculate work done when given 3 different distances?

The work done can be calculated by multiplying the force applied by the object by the total distance traveled. In this case, if there are 3 different distances, you would need to calculate the work done for each distance separately and then add them together to get the total work done.

2. Can you provide an equation for finding work done with 3 different distances?

Yes, the equation for calculating work done is W = F x d, where W is the work done, F is the force applied, and d is the distance traveled. To find the work done with 3 different distances, you would use the equation W1 + W2 + W3, where W1, W2, and W3 are the work done for each distance.

3. What units are used for measuring work done?

The standard unit for measuring work done is joules (J). However, depending on the system of measurement being used, other units such as foot-pounds (ft-lb) or Newton-meters (N-m) can also be used.

4. Is the direction of the object's movement important when calculating work done with 3 different distances?

Yes, the direction of the object's movement is important when calculating work done. Work is a scalar quantity, meaning it has magnitude but no direction. However, the displacement (distance traveled) is a vector quantity, meaning it has both magnitude and direction. Therefore, the direction of the object's movement would affect the calculation of work done.

5. What is the significance of finding work done with 3 different distances?

Finding work done with 3 different distances can be used to determine the total amount of energy transferred to or from an object. This information can be useful in various fields such as physics, engineering, and sports, to name a few.

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