In each of the following a force, F is acting on an object of mass, m. The direction of displacement is from west to east shown by the longer arrow. Observe the diagrams carefully and state whether the work done by the force is negative, positive or zero.
Solution and Explanation
(i)
Since in this diagram displacement is perpendicular to the direction of force, so work done is zero.
(ii)
Since in this diagram displacement is in the direction of force, so work done is positive.
(iii)
Since in this diagram displacement is in the opposite direction of the force applied hence work done is negative.
Top Questions on Work
- In an actual regenerative Rankine cycle, the net work out put will be _____ as compared to simple Ranking cycle.
- A metal has work function \(w_0\) = 3.3×10-19 J. What should be the minimum frequency of the incident radiation that can remove an electron from the metal surface? [Given h = 6.6x10-34 J-s]
- Look at the activities listed below. Reason out whether or not work is done in the light of your understanding of the term ‘work’.
• Suma is swimming in a pond.
• A donkey is carrying a load on its back.
• A wind-mill is lifting water from a well.
• A green plant is carrying out photosynthesis.
• An engine is pulling a train.
• Food grains are getting dried in the sun.
• A sailboat is moving due to wind energy. - An object of mass, m is moving with a constant velocity, v. How much work should be done on the object in order to bring the object to rest?
- Calculate the work required to be done to stop a car of 1500 kg moving at a velocity of 60 km/h?
Questions Asked in CBSE Class IX exam
- Here is your diary entry when you visited Agra. Read the points and try to write a travelogue describing your visit to Agra and the Taj Mahal. You may add more details.
January 2003 — rise before dawn — take the Shatabdi Express at 6.15 a.m. from Delhi — meet a newly-married couple on train — talk about Himachal Pradesh — get off the train — enter the once-grand city, Agra — twisted alleys — traffic dense — rickshaws, cars, people — vendors selling religious artifacts, plastic toys, spices and sweets — go to the Taj Mahal — constructed entirely of white marble — magical quality — colour changes with varying of light and shadow — marble with gemstones inside — reflection of the Taj Mahal in the pond — school-children, tourists — tourist guides following people.- CBSE Class IX
- Kathmandu
- 1.The (site, cite) of the accident was (ghastly/ghostly).
2. Our college (principle/principal) is very strict.
3. I studied (continuously/continually) for eight hours.
4. The fog had an adverse (affect/effect) on the traffic.
5. Cezanne, the famous French painter, was a brilliant (artist/artiste).
6. The book that you gave me yesterday is an extraordinary (collage/college) of science fiction and mystery. 7. Our school will (host/hoist) an exhibition on cruelty to animals and wildlife conservation.
8. Screw the lid tightly onto the top of the bottle and (shake/shape) well before using the contents.- CBSE Class IX
- If I were you
- Is there any difference between the two roads as the poet describes them:
(i) in stanzas two and three?
(ii) in the last two lines of the poem?- CBSE Class IX
- The fun they had
- Discuss what these phrases mean to you.
(i) a yellow wood
(ii) it was grassy and wanted wear
(iii) the passing there
(iv) leaves no step had trodden black
(v) how way leads on to way- CBSE Class IX
- The fun they had
- A driver of a car travelling at \(52\) \(km \;h^{–1}\) applies the brakes Shade the area on the graph that represents the distance travelled by the car during the period. (b) Which part of the graph represents uniform motion of the car?
- CBSE Class IX
- Graphical Representation of Motion
Concepts Used:
Work
Work is the product of the component of the force in the direction of the displacement and the magnitude of this displacement.
Work Formula:
W = Force × Distance
Where,
Work (W) is equal to the force (f) time the distance.
Work Equations:
W = F d Cos θ
Where,
W = Amount of work, F = Vector of force, D = Magnitude of displacement, and θ = Angle between the vector of force and vector of displacement.
Unit of Work:
The SI unit for the work is the joule (J), and it is defined as the work done by a force of 1 Newton in moving an object for a distance of one unit meter in the direction of the force.
Work formula is used to measure the amount of work done, force, or displacement in any maths or real-life problem. It is written as in Newton meter or Nm.