Let's solve each question step-by-step.
### Question 3
A postal service worker lifts a package into a truck. She exerts 22 Joules (J) of work lifting the package for 4 seconds.
We need to determine the power used. Power (P) is given by the formula:
[tex]\[ P = \frac{\text{Work done}}{\text{Time taken}} \][/tex]
Given:
- Work done (W) = 22 J
- Time taken (t) = 4 seconds
Using the formula:
[tex]\[ P = \frac{22 \, \text{J}}{4 \, \text{s}} = 5.5 \, \text{W} \][/tex]
Therefore, the power used by the postal service worker is:
[tex]\[ B. \, 5.5 \, \text{W} \][/tex]
### Question 4
A truck pulls a block 8 meters across a level surface at a force of 216 Newtons (N) over the course of 12 seconds.
We need to determine the power used. First, we calculate the work done.
Work done (W) is given by the formula:
[tex]\[ W = \text{Force} \times \text{Distance} \][/tex]
Given:
- Force (F) = 216 N
- Distance (d) = 8 meters
Using the formula:
[tex]\[ W = 216 \, \text{N} \times 8 \, \text{m} = 1728 \, \text{J} \][/tex]
Now, we calculate the power. Power (P) is given by the formula:
[tex]\[ P = \frac{\text{Work done}}{\text{Time taken}} \][/tex]
Given:
- Work done (W) = 1728 J
- Time taken (t) = 12 seconds
Using the formula:
[tex]\[ P = \frac{1728 \, \text{J}}{12 \, \text{s}} = 144 \, \text{W} \][/tex]
Therefore, the power used by the truck is:
[tex]\[ C. \, 144 \, \text{W} \][/tex]
