(a) How much work is done in lifting a 1.3-kg book off the floor to put it on a desk that is 0.9 m high? Use the fact that the acceleration due to gravity is g = 9.8 m/s². (b) How much work is done in lifting a 21-lb weight 4 ft off the ground? olution (a) The force exerted is equal and opposite to that exerted by gravity, so the force is F = m = mg = (1.3) (9.8) = d²s dt² and then the work done is W = Fd= (0.9) = N J. (b) Here the force is given as F= 21 lb, so the work done is W = Fd = 21.4 = ft-lb. Notice that in part (b), unlike part (a), we did not have to multiply by g because we were given the weight (which is a force) and not the mass of the object.

College Physics
11th Edition
ISBN:9781305952300
Author:Raymond A. Serway, Chris Vuille
Publisher:Raymond A. Serway, Chris Vuille
Chapter1: Units, Trigonometry. And Vectors
Section: Chapter Questions
Problem 1CQ: Estimate the order of magnitude of the length, in meters, of each of the following; (a) a mouse, (b)...
icon
Related questions
Topic Video
Question

Please answer all parts and show work

(a) How much work is done in lifting a 1.3-kg book off the floor to put it on a desk that is 0.9 m high? Use the fact that the acceleration due to gravity is g = 9.8 m/s².
(b) How much work is done in lifting a 21-lb weight 4 ft off the ground?
Solution
(a) The force exerted is equal and opposite to that exerted by gravity, so the force is
F = m = mg = (1.3) (9.8) =
d²s
dt²
and then the work done is
W = Fd =
(0.9) =
N
J.
(b) Here the force is given as F = 21 lb, so the work done is
W = Fd = 21. 4 =
ft-lb.
Notice that in part (b), unlike part (a), we did not have to multiply by g because we were given the weight (which is a force) and not the mass of the object.
Transcribed Image Text:(a) How much work is done in lifting a 1.3-kg book off the floor to put it on a desk that is 0.9 m high? Use the fact that the acceleration due to gravity is g = 9.8 m/s². (b) How much work is done in lifting a 21-lb weight 4 ft off the ground? Solution (a) The force exerted is equal and opposite to that exerted by gravity, so the force is F = m = mg = (1.3) (9.8) = d²s dt² and then the work done is W = Fd = (0.9) = N J. (b) Here the force is given as F = 21 lb, so the work done is W = Fd = 21. 4 = ft-lb. Notice that in part (b), unlike part (a), we did not have to multiply by g because we were given the weight (which is a force) and not the mass of the object.
Expert Solution
Step 1: Introduce the formula of workdone

The work done is the product of force and displacement along the force direction. 


steps

Step by step

Solved in 4 steps

Blurred answer
Knowledge Booster
Mechanical Work done
Learn more about
Need a deep-dive on the concept behind this application? Look no further. Learn more about this topic, physics and related others by exploring similar questions and additional content below.
Recommended textbooks for you
College Physics
College Physics
Physics
ISBN:
9781305952300
Author:
Raymond A. Serway, Chris Vuille
Publisher:
Cengage Learning
University Physics (14th Edition)
University Physics (14th Edition)
Physics
ISBN:
9780133969290
Author:
Hugh D. Young, Roger A. Freedman
Publisher:
PEARSON
Introduction To Quantum Mechanics
Introduction To Quantum Mechanics
Physics
ISBN:
9781107189638
Author:
Griffiths, David J., Schroeter, Darrell F.
Publisher:
Cambridge University Press
Physics for Scientists and Engineers
Physics for Scientists and Engineers
Physics
ISBN:
9781337553278
Author:
Raymond A. Serway, John W. Jewett
Publisher:
Cengage Learning
Lecture- Tutorials for Introductory Astronomy
Lecture- Tutorials for Introductory Astronomy
Physics
ISBN:
9780321820464
Author:
Edward E. Prather, Tim P. Slater, Jeff P. Adams, Gina Brissenden
Publisher:
Addison-Wesley
College Physics: A Strategic Approach (4th Editio…
College Physics: A Strategic Approach (4th Editio…
Physics
ISBN:
9780134609034
Author:
Randall D. Knight (Professor Emeritus), Brian Jones, Stuart Field
Publisher:
PEARSON