2. Work done is when a force moves the point at
which it acts in the direction of the force
Work done = force*distance moved
Work done for displacement x = force*x*cos
4. Ep = mass*gravity*chanhe in height
Ek = ½*mass*volume
Ep = Ek
5. Efficiency = useful work done/total energy
input
It may be given as a ratio or percentage
6. It says that if the elastic limit is not exeeded,
the extention is proportional to the aplied
load
Force = constant*extention
7. Strain = ½*constant*extention^2
Strain energy is energy stored in a body due
to a change of shape
8. It is the constant for a material of an object
Strain = extention/original length
Stress = force/area
Young modulus = stress/strain
9. The maximum stress a wire could support, if
the fracture is gradual it is ductile, if the
fracture is sudden it is brittle
10. When the object returns to its original length
with a diffrent path because of excess energy
11. How much energy is needed to raise the
temperature of a substance
Energy needed = mass*spesific heat
capacity*temperature change
12. The energy needed to raise the temperature
of an object by one degree
Energy needed = mass*thermal (heat)
capacity*temperature change
13. The energy needed to change the state of an
object
Energy needed = mass*latent heat of fusion
or vaporisation
14. Power = work done/time taken
Power = force*speed
15. It is the turning effect of a force, it is defined
as the product of the force and the
perpendicular distance of the line of action of
the force from the pivot
Moment of force = force*length*cos
16. A couple consists of 2 forces equal in
magnitude, but opposite in direction with
diffrent lines of action
The tourqe of a couple is the product of one
of the forces and the perpendicular distance
between the forces
17. It states that for a body to be in rotational
equilibrium the sum of the clockwise
moments about any point must equal the
sum of the anticlockwise moments about the
same point
18. The centre of gravity of an object is the point
at which the whole weight of the object may
be considered to act
For a body to be in equilibrium:
1. The sum of the forces in any direction must
be zero
2. The sum of the moments of the forces
about any point must be zero
