Question

exam lesson name: energy conversions
exam number: 700697rr
exam guidelines
exam instructions
question 15 of 20 :
select the best answer for the question.

1. a moving company is asked to relocate 520 bricks to a location 15 meters above the ground. if each brick is 4 kilograms, what amount of work will be needed to accomplish the task?

a. 203,840 j
b. 229,320 j
c. 305,760 j
d. 588,000 j
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Explanation:

Step1: Recall work formula for lifting

Work done against gravity is \( W = mgh \), where \( m \) is mass, \( g = 9.8 \, \text{m/s}^2 \), \( h \) is height. First, find total mass of bricks.
Total mass \( m = 520 \times 4 = 2080 \, \text{kg} \)

Step2: Calculate work

Substitute \( m = 2080 \, \text{kg} \), \( g = 9.8 \, \text{m/s}^2 \), \( h = 15 \, \text{m} \) into \( W = mgh \).
\( W = 2080 \times 9.8 \times 15 \)
First, \( 2080 \times 9.8 = 20384 \)
Then, \( 20384 \times 15 = 305760 \, \text{J} \)

Answer:

C. 305,760 J