A motor with a power of 7.0 × 104 watts lifts a loaded elevator to a height of 20.00 meters for 40 seconds. What is the force exerted by the motor on the elevator?
A. 1.4 × 104 newtons
B. 7.0 × 104 newtons
C. 1.4 × 105 newtons
D. 2.1 × 105 newtons
E. 3.5 × 105 newtons

Question

A motor with a power of 7.0 × 104 watts lifts a loaded elevator to a height of 20.00 meters for 40 seconds. What is the force exerted by the motor on the elevator?
 A. 1.4 × 104 newtons 
B. 7.0 × 104 newtons 
C. 1.4 × 105 newtons 
D. 2.1 × 105 newtons 
E. 3.5 × 105 newtons

shubhamsrg · Answer

power = work/time = force*distance/time 

Just substitute values.

kropot72 · Answer

There are two ways to calculate the work done:
1. Work = watt second =$$7\times 10^{4}\times 40\ joules\ ..........(1)$$
2. Work = Newton meters = $$N \times 20\ joules\ ..........(2)$$
To find the value of N we equate equations (1) and (2) and solve for N.
$$N \times 20=7\times 10^{4}\times 40$$
Note: Don't forget to convert your answer to scientific notation.