Schaum's Outline of College Physics, Twelfth Edition (Schaum's Outlines)
Schaum's Outline of College Physics, Twelfth Edition (Schaum's Outlines)
12th Edition
ISBN: 9781259587399
Author: Eugene Hecht
Publisher: McGraw-Hill Education
bartleby

Videos

Textbook Question
100%
Book Icon
Chapter 7, Problem 10SP

A motor furnishes 120 hp to a device that lifts a 5000-kg load to a height of 13.0 m in a time of 20 s. Find the efficiency of the machine.

Expert Solution & Answer
Check Mark
To determine

The efficiency of a machine, considering the motor delivers a power of 120 hp to a device, which lifts a 5000 kg load to a height of 13.0 m in 20 s.

Answer to Problem 10SP

Solution:

36%

Explanation of Solution

Given data:

The power delivered by the motor to the device is 120 hp.

The mass of the lifted load is 5000 kg.

The height to which the load was lifted is 13.0 m.

The time taken to lift the load to the height is 20 s.

Formula used:

The formula for efficiency of a machine is

η=PoPi×100%

Here, η is the efficiency of the machine;Po and Pi represent the output power and input power of the machine, respectively.

The work done is calculated by the formula:

w=(F)(S)

Here, w is the work done, F is the force, and S is the displacement in the direction of force F.

Power is calculated by the formula:

P=wt

Here, P is the power and t is the time taken to do the work w.

The formula for weight of a body is

W=mg

Here, W is the weight of the body, m is the mass of the body, and g is the acceleration due to gravity.

Explanation:

Consider the expression for weight of the lifted load as

W=mg

The standard value of g is 9.81 m/s2.

Substitute 5000kg for m and 9.81 m/s2 for g

W=(5000kg)(9.81 m/s2)=49,050 N

Consider the expression for work done to lift the load to a height of 13.0 m as

w0=Wh

Here, h is the height to which the load is lifted and w0 is the corresponding work done.

Substitute 49050 N for F and 13.0 m for S

w0=(49,050 N)(13.0 m)=637,650 J

Calculate the power delivered by the machine by the formula:

Po=w0t

Here, t is the time taken to lift the load to the height of 13.0 m.

Substitute 20 s for t and 637650 J for w0

Po=637650 J20 s=31882.5 W=(31882.5 W)(1hp745.7W)=42.76 hp

Consider the expression for efficiency of a machine:

η=PoPi×100%

Substitute 42.76 hp for Po and 120 hp for Pi

η=42.76 hp120 hp×100%36%

Conclusion:

The efficiency of the machine is 36%.

Want to see more full solutions like this?

Subscribe now to access step-by-step solutions to millions of textbook problems written by subject matter experts!
Students have asked these similar questions
What is integrated science. What is fractional distillation What is simple distillation
19:39 · C Chegg 1 69% ✓ The compound beam is fixed at Ę and supported by rollers at A and B. There are pins at C and D. Take F=1700 lb. (Figure 1) Figure 800 lb ||-5- F 600 lb بتا D E C BO 10 ft 5 ft 4 ft-—— 6 ft — 5 ft- Solved Part A The compound beam is fixed at E and... Hình ảnh có thể có bản quyền. Tìm hiểu thêm Problem A-12 % Chia sẻ kip 800 lb Truy cập ) D Lưu of C 600 lb |-sa+ 10ft 5ft 4ft6ft D E 5 ft- Trying Cheaa Những kết quả này có hữu ích không? There are pins at C and D To F-1200 Egue!) Chegg Solved The compound b... Có Không ☑ ||| Chegg 10 וח
No chatgpt pls will upvote
Knowledge Booster
Background pattern image
Physics
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.
Similar questions
SEE MORE QUESTIONS
Recommended textbooks for you
Text book image
Glencoe Physics: Principles and Problems, Student...
Physics
ISBN:9780078807213
Author:Paul W. Zitzewitz
Publisher:Glencoe/McGraw-Hill
Text book image
University Physics Volume 1
Physics
ISBN:9781938168277
Author:William Moebs, Samuel J. Ling, Jeff Sanny
Publisher:OpenStax - Rice University
Work-Energy Theorem | Physics Animation; Author: EarthPen;https://www.youtube.com/watch?v=GSTW7Mlaoas;License: Standard YouTube License, CC-BY