work done by student

1. *A presentation by shivam chauhan
and sourabh suman

2. WORK

3. 1.Positive work done
2.Negative work done
3.Zero work done

4. Positive workdone

5. If angle between force applied and direction of
displacement is obtuse it is said to be negative
work done

6. When angle between the force applied and displacement
is right angle then it is said to be zero work done.

7. 1.KINETIC ENERGY
2.POTENTIAL ENERGY
The ability of doing work is called energy.

8. Energy possessed due to its motion then it is
called kinetic energy .
KE = ½ mv²
Eg: Moving bus ,Playing child ,Running Athlete.

9. Energy possessed due to its position is called potential energy.
U = mgh
Eg: when the car slowly- slowly climbs the hill ,the potential energy is stored
in the car because of its position.

10. The gravitational potential energy of two particles of masses M and m
separated by a distance r is given by
U = -GMm
r
Where G = universal gravitational constant
= 6.67 × 10¯11 Nm²kg¯²

11. The work done by spring force is -1/2kx² when the spring is stretched or
compressed by an amount x from its unstretched position. Thus ,
U = -W = -(-1/2kx²)
U = 1/2kx²
Where k = spring constant

12. The change in kinetic energy is
equal to the total work done on it
by the net force

13. Conservation of energy

14. If work done by force depends only on initial and final states and not
on the path taken , it is called a conservative force.
Eg. Gravitational, Electrostatic Forces .

15. If work done by a force depends upon the initial and final states as well as
depends on the path taken it is called non-conservative forces .
Eg: Force of friction , Magnetic force .

16. The rate of doing work or transfer of energy is called power
Power = work
time
Dimension = [ML²T‾³] . SI Unit = watt , watt = 1J/s .
There is another unit of power , namely horse power (hp) ,
1 hp = 746W
Commercial unit of energy is kilo-watt hour .
1kWh = 1000(W) × 3600(s)= 3600000 J

18. *Kinetic energy is conserved.
*Total linear momentum is conserved.

20. Inelastic collision
When initial kinetic energy is not equal to the
final kinetic energy is called inelastic collision.

21. PRESENTATIONBY : SHIVAMAND SAURABH
DIRECTEDBY:NAGENDRAPANDEY