This slide describes the idea of work and work-done and various idea and principles about energy and its utilization. It defines the basic aspects of work and how it is related to each other

1. WORK, ENERGY
AND POWER

2. PRESENTED BY:
AROSEK PADHI - CL – XI

3. A SIMPLE QUESTION.
ARE THEY WORKING

5. Is this guy working ? Yes he seems to push the wall. But
No, he is not working. To know why he’s not working let’s
know a few things about WORK and WORK
DONE
This guy is working !! Well,…He’s going to office to
WORK as it may seem.

6. WORK

7. IF A FORCE 𝑭 IS APPLIED ON A BODY IN A DIFFERENT
DIRECTION OF DISPLACEMENT OF THE BODY AND THE
BODY UNDERGOES A DIAPLACEMENT 𝒅 IN THE POSITIVE
X – DIRECTION, THE WORK DONE BY THE FORCE IS
DEFINED AS THE PRODUCT OF COMPONENT OF THE
FORCE IN THE DIRECTION OF THE DISPALCEMENT AND
THE MAGNITUDE OF THIS DISPLACEMENT

8. W = (FcosƟ)d = 𝐹. 𝑑

9. IN TERMS OF
UNITS…..

10. WORK IS SAID TO BE 1 JOULE, WHEN A
FORCE OF ONE NEWTON ACTUALLY MOVES
A BODY THROUGH A DISTANCE OF ONE
METRE IN THE DIRECTION OF THE APPLIED
FORCE.
WORK IS SAID TO BE ONE kg-m, WHEN A
FORCE OF 1 kgf (or 1 kg wt) MOVES A BODY
THROUGH A DISTANCE OF 1m IN THE
DIRECTION OF THE APPLIED FORCE.
WORK IS SAID TO BE ONE g-cm, WHEN A
FORCE OF 1 gf MOVES A BODY THROUGH A
DISTANCE OF 1 cm IN THE DIRECTION OF
THE APPLIED FORCE
WORK IS SAID TO BE 1 ERG, WHEN A FORCE
OF ONE DYNE ACTUALLY MOVES A BODY
THROUGH A DISTANCE OF ONE
CENTIMETRE IN TE DIRECTION OF THE
APPLIED FORCE.

11. KINETIC
ENERGY

13. DERIVATION OF
KINETIC ENERGY
BY CALCULUS
METHOD

15. RELATION BETWEEN KINETIC
ENERGY AND LINEAR
MOMENTUM

16. WHEN A BODY SLIDE d DISTANCE ONAROUGH
HORIZONTAL SURFACEWITHVELOCITY V, ITS
STOPPING DISTANCE S GIVEN BY:

17. THE
WORK-
ENERGY
THEOREM

18. WORK ENERGY THEOREM IS AN INTEGRAL FORM OF
NEWTON’S 2ND LAW. IT DOES NOT, IN GENERAL
INCORPORATE THE COMPLETE DYNAMICAL INFORMATION
OF 2ND LAW, WHICH IS A RELATION BETWEEN FORCE AND
ACCERELATION AT ANY TIME. THE W-E THEOREM
INVOLVES AN INTEGRAL OVER AN INTERVAL OF TIME. THE
TEMPORAL (TIME) INFORMATION CONTAINED IN THE 2ND
LAW IS INTEGRATED OVER AND IS NOT AVAILABLE
EXPLICITLY.

19. THE CONSERVATION OF
MECHANICAL ENERGY
THE TOTAL MECHANICAL ENERGY OF A SYSTEMIS
CONSERVED IF THE FORCES DOING WORK ON OT, ARE
CONSERVATIVE.

20. A FORCE IS CONSERVATIVE IF IT CAN BE
DERIVED FROM A SCALAR QUANTITY.
THE WORK DONE BY THE
CONSERVATIVE FORCE DEPENDS ONLY
ON THE END POINTS
WORK DONE BY THE CONSERVATIVE
FORCE IN A CLOSED PATH IS ZERO. THIS
IS APPARENT AS Xi = Xf

21. PROPERTIES OF CONSERVATIVE AND
NON- CONSERVATIVE FORCES

22. MOTION
IN A
VERTICAL
CIRCLE

24. POTENTIAL ENERGY CURVE AND
EQUILIBRIUM SYSTEM
AN OBJECT IS SAID TO BE IN STABLE
EQUILIBRIUM, IF ON SLIGHT
DISPLACEMENT FROM EQUILIBRIUM
POSITION IT HAS TENDENCY TO COME
BACK TO ITS ORIGINAL POSITION. IN THIS
CASE OF STABLE EQUILIBRIUM THE
POTENTIAL ENERGY IS MINIMUM.
AN OBJECT IS SAID TO BE IN UNSTABLE
EQUILIBRIUM, IT ON SLIGHT
DISPLACEMENT FROM EQUILIBRIUM
POSITION IT MOVES IN THE DIRECTION
OF DISPLACEMENT. THE POTENTIAL
ENERGY IS MAXIMUM IN EQUILLIBRIUM
STATE.

26. POWER IS DEFINED AS THE TIME RATE AT
WHICH WORK IS DONE OR ENERGY IS
TRANSFERRED. THE AVERAGE POWER OF A
FORCE IS DEFINED AS THE RATIO OF THE
WORK, W TO THE TOAL TIME t TAKEN
P =
𝒅𝑾
𝒅𝒕

27. COLLISION
TYPES:- (on the basis of
dimensions)
1D COLLISION
2D COLLISION
TYPES:-
ELASTIC
INELASTIC
SEM-IELASTIC

28. EXPRESSIONS FOR
VELOCITIES OF THE
BODIES AFTER THE
1D ELASTIC
COLLISION

32. 2D ELASTIC
COLLISION

33. Hence,
ɸ + Ɵ = 900

34. PERFECTLY INELASTIC
COLLISION

35. IF THE MAXIMUM DEORMATION IN THE
COLLIDING BODIES DURING THE
DEFORMING PERIOD IS NOT RECOVERED
AT ALL, THE COLISION IS SAID TO BE
PERFECTLY INELASTIC

36. NOTE:
IF WE PUT e = 1, IN THE ABOVE EQUATION, THEN WE WILL GET THE VELOCITIES OF THE BODIES
AFTER COLLISION IN ELASTIC CONDITION.