Question

How much work is done in lifting a 1.4-kg book off the floor to put it on a desk that is 0.7 m high?

Use the fact that the acceleration due to gravity is g = 9.8 m/s^2. How much work is done in lifting a 21-lb weight 6 ft off the ground?

Answer 1

Answer:

Step-by-step explanation:

Work is said to be done when a force applied to an object cause the body to move in a specified direction.

Work-done = Force * Distance

Since Force = mass * acceleration due to gravity

Work-done =  mass * acceleration due to gravity * distance

Given mass = 1.4kg, distance = 0.7m and g = 9.8m/s²

Workdone in lifting the book off the floor = 1.4*0.7*9.8

Workdone = 9.604Joules

- Similarly, work done in lifting a 21-lb weight book 6 ft off the ground is expressed using the same formula as above;

Given mass = 21-lb, g = 32ft/s² and distance = 6ft

Workdone = 21 * 32 * 6

Workdone = 4,032 lb-ft²/s²

Hence, work-done in lifting a 21-lb weight book 6 ft off the ground is  4,032 lb-ft²/s²