Question

Hello! Im new to brainly and want to know if any one can help me with these questions :)

1. How much force is used if 60J of work were necessary to lift an object 3m?

A.
180N

B.
0.05N

C.
20N

D.
200N

2. How much power is used to push a car with a force of 870N a distance of 65m in 500 seconds? Explain.

3. Calculate the efficiency of a machine with a work output of 3100j and a work input of 4600j.

A.
1.48%

B.
148%

C.
6.73%

D.
67.39%


( BTW I only ask 3 questions at a time so that it's easy for the friendly people :) )

Answer 1

Answer:

1

Work = Force × displacement

60 = F × 3

F = 60/3 = 20 N

2

First calculate work done

Work = Force × displacement

W = 870 × 65 J

Now power = Work / time

$p = \frac{870 \times 65}{500} = 113.1 \: w$

3

Work efficiency = output/input × 100

$= \frac{3100}{4600} \times 100 = 67.39\%$