Question

If you perform 40 J of work lifting a 10-N box from the floor to a shelf, how high is the shelf?


4.0 m

0.3 m

20 m

400 m

Answer 1

To find the height of the shelf, we can use the work-energy principle, which states that work done (W) is equal to the force (F) applied multiplied by the distance (d) moved in the direction of the force:

\[ W = F \cdot d \]

In this case, we have:

- Work done (W) = 40 J
- Force (F) = weight of the box = 10 N

We need to find the distance (d), which corresponds to the height (h) of the shelf. Rearranging the equation to solve for distance gives us:

\[ d = \frac{W}{F} \]

Substituting in the values we have:

\[ d = \frac{40 \, \text{J}}{10 \, \text{N}} = 4 \, \text{m} \]

So, the height of the shelf is **4.0 m**.