- Online Test Series
- Final Revision Module (3 Books)
- 5 Mock Tests
- 5 Diagnostic Tests
- 15 Practice Tests
- Sample Papers With Solutions
- Past Year Papers With Solutions
- Ask The Expert
- On Call Mentorship
Work is said to be done by a force when the force produces a displacement in the body on which it acts in any direction except perpendicular to the direction of the force.
Work done by constant force
Consider an object undergoes a displacement S along a straight line while acted on a force F that makes an angle θ with S as shown.
The work done W by the agent is the product of the component of force in the direction of displacement and the magnitude of displacement.
i.e., W=FS Cosθ …..(1)
Work done is a scalar quantity and its S.I. unit is N-m or joule (J). We can also write work done as a scalar product of force and displacement.
Where S is the displacement of the point application of the force.
From this definition, we conclude the following points
Work done by a force is zero If displacement is perpendicular to the force (θ 90o)
Important points about work:
UNITS OF WORK:
In case system, the unit of work is erg. One erg of work is said to be done when a force of one dyne displaces a body through one centimetre in its own direction.
1 erg = 1 dyne × 1 cm = 1 g cm s–2 × 1 cm = 1 g cm2
Note: Another name for joule is newton metre
Relation between joule and erg
1 joule = 1 newton ×1 metre
1 joule = 105 dyne × 102 cm = 107 dyne cm
1 joule = 107 erg
1 erg = 10–7 joule
Dimensions of Work:
[Work] = [Force] [Distance] = [MLT–2] [L] = [ML2T–2]
Work has one dimension in mass, two dimensions in length and ‘–2’ dimensions in time, On the basis of dimensional formula, the unit of work is kg m2 s–2.
Note that 1 kg m2s–2 = (1 kg m s–2) m = 1 N m = 1 J.
Work done by multiple Forces:
If several forces act on a particle, then we can replace F in equation W=F.S by the force
The gives the work done by the net force during a displacement S of the particle.
We can rewrite equation (i) as:
So, the work done on the particle is the sum of the individual work done by all the forces acting on the particle.
W= Fs cos Φ =
F(x)= - ΔU /Δx
1 watt= 1 joule/second
By learning in meritnation I got B2, but by learning topper learning I got A1... so which is the best. This is awesome to learn and easy to study science. At 1st term I got B2 but at 2nd term I got A1.
Manoj Vijay CBSE class IX
Excellent Faculty! I have been studying from topperlearning.com since Class IX and have consistently scored above 90% in my these 4 years.I studied throughout nights to achieve my goal.Moreover, becoming Rank 1 on topperlearning boosted my confidence to high skies.Thank you topperlearning, without you I would not have been able to score 91.2% in Class XII Boards(2015) and CGPA 9.8 in my Class X Boards(2013). Hope that topperlearning will continue to help students throughout India, creating a brighter future for them. Regards, Vivek Saahil
Vivek Saahil CBSE class XII Science
I like topper learning because I can understand the level I have prepared for my subject and study better.
Mohanapriya Saravanakumar CBSE class X
Topperlearning is really a very good helping tool. Every time I had doubts related to any concept in PCM I posted it and immediately my problem was solved. It also helped me in scoring good ranks in competitive exams too. The topper faculty is very good. The teachers explained each and every concept in depth. My favourite teacher is Physics teacher
Sahibdeep Singh Sodhi CBSE class XII Science
We all know that audio-visual medium is a better way of explaining and educating the students. It not only makes learning fun but also gives the message more clearly and precisely. Topper is a very good amalgamation of good teaching and good learning methods.
Sonia Malik, Professor
VV DAV School, New Delhi class ALL Class
Queries asked on Sunday and after 7 pm from Monday to Saturday will be answered after 12 pm the next working day.
a man drags a block through 10m on rough surface (mew=0.5). A force of root3 kN acting at 30 to the horizontal . the work done by applied force is
A body is displaced by 20 m, when a force of 20N acts on the body. The work done is
Sir pls solve the following.