Question

1. a person weighing 600 n gets on an elevator. the elevator lifts the person 6 m in 10 seconds. how much power was used?
2. how much time is needed to produce 720 joules of work if 90 watts of power is used?
3. if 69 w of power is produced in 18 seconds, how much work is done?
4. a set of pulleys lifts an 800 n crate 4 meters in 7 seconds. what power was used?

Explanation:

Problem 9

Step1: Calculate work done

Work \( W = F \times d \), where \( F = 600 \, \text{N} \), \( d = 6 \, \text{m} \).
\( W = 600 \times 6 = 3600 \, \text{J} \)

Step2: Calculate power

Power \( P = \frac{W}{t} \), where \( t = 10 \, \text{s} \).
\( P = \frac{3600}{10} = 360 \, \text{W} \)

Step1: Recall power formula

Power \( P = \frac{W}{t} \), so \( t = \frac{W}{P} \).

Step2: Substitute values

\( W = 720 \, \text{J} \), \( P = 90 \, \text{W} \).
\( t = \frac{720}{90} = 8 \, \text{s} \)

Step1: Recall power formula

Power \( P = \frac{W}{t} \), so \( W = P \times t \).

Step2: Substitute values

\( P = 68 \, \text{W} \), \( t = 18 \, \text{s} \).
\( W = 68 \times 18 = 1224 \, \text{J} \)

Answer:

360 W

Problem 10