English

Look at the activity below. Reason out whether or not work is done in the light of your understanding of the term ‘work’. Food grains are getting dried in the sun. - Science

Advertisements
Advertisements

Question

Look at the activity below. Reason out whether or not work is done in the light of your understanding of the term ‘work’.

Food grains are getting dried in the sun.

Short Answer

Solution

The grains of corn are drying in the heat of the sun; here, also, no work is being done because the grains are stable in their place. There is no displacement in them.

shaalaa.com
  Is there an error in this question or solution?
Chapter 11: Work and Energy - Exercises [Page 158]

APPEARS IN

NCERT Science [English] Class 9
Chapter 11 Work and Energy
Exercises | Q 1. 6 | Page 158

Video TutorialsVIEW ALL [1]

RELATED QUESTIONS

Can there be displacement of an object in the absence of any force acting on it? Think. Discuss this question with your friends and teacher.


Explain briefly why the work done by a fielder when he takes a catch in a cricket match is negative.


A force acts on a body and displaces it by a distance S in a direction at an angle θ with the direction of the force. What should be the value of θ to get the maximum positive work?


A coolie does no work against the force of gravity while carrying a luggage on a road.


The moon is revolving around the earth in a circular path. How much work is done by the moon?


Write the expression for work done by a force.


.A man raises a box of mass 50kg to a height of 2m in 20s, while another man raises the same box to the same height in 50s. Compare:

(i) the work done, and

(ii) the power developed by them.


What are the units of (a) work, and (b) energy?


What is the work done against gravity when a body is moved horizontally along a frictionless surface?


Fill in the blank with suitable word :
Work is measured as a product of __________ and __________


A person of mass 50 kg climbs a tower of height 72 metres. Calculate the work done. (g = 9.8 m s−2).


A girl is carrying a school bag of 3 kg mass on her back and moves 200 m on a levelled road. If the value of g be 10 m/s2, the work done by the girl against the gravitational force will be :


It takes 20 s for A to climb up the stairs, while B does the same in 15 s. compare the (i) work done, and (ii) power developed by A and B.

Can a body possess zero kinetic energy?

What is the amount of energy spent in lifting 1 kg through 1 m? Take g = 10 ms-2.

A body is pivoted at a point. A force of 10 N is applied at a distance of 30 cm from the pivot. Find the moment of force about the pivot.

(a) Define power and name its unit.
(b) A girl weighting 50 kg climbs up 60 steps each of 20 cm height in 5 minutes. Calculate the power developed.


Give an example 
Chemical energy changes to heat energy.


What is power? How do you differentiate kilowatt from kilowatt-hour? The Jog Falls in Karnataka state are nearly 20 m high. 2000 tonnes of waterfalls from it in a minute. Calculate the equivalent power if all this energy can be utilized? (g = 10 m s–2)


A man squatting on the ground gets straight up and stand. The force of reaction of ground on the man during the process is ______.


Share
Notifications

Englishहिंदीमराठी


      Forgot password?
Use app×