Work is done if the object you push changes it direction towards which you are pushing it. No work is done if the force you exert does not make the object move.

1. Work and Energy

4. •Work is done if the
object you push
changes it direction
towards which you
are pushing it.

6. •No work is done if the
force you exert does
not make the object
move.

8. •No work is done if the
force you exert does not
make the object move in
the same direction as the
force you exerted

19. • The unit, joule (J) is named after
the English Physicists James
Prescott Joule. This is also a
unit of energy. One (1) Joule is
equal to the work done or
energy expended in applying a
force of one Newton through a
distance of one meter.

21. Work is a method of Transferring
Energy

23. Kinetic energy
• The energy of a moving object is
called energy of motion or kinetic
energy (KE)

24. Example of kinetic energy

25. A racing car

26. A bullet in motion

27. A stream of water

29. THREE TYPES of kinetic
energy
1. vibrational kinetic energy or the energy
due to vibrational motion
Small and rapid to-and-fro motion of a body
about its mean position is called vibrational
motion. The kinetic energy of a body by
virtue of its vibrational motion is called
vibrational kinetic energy.
Example: Vibrating the string of a guitar, a
tuning fork struck against a rubber block,
etc., possess vibrational kinetic energy.

30. 2. Rotational kinetic energy
• -the energy due to rotational motion
• When a body rotates on its axis, it is
said to possess rotational motion. The
kinetic energy of a body by virtue of
its rotational motion is called
rotational kinetic energy.
• Example: The moving blades of a
ceiling fan, a spinning top, a potter’s
wheel, etc., possess rotational kinetic
energy.

31. 3. Translational kinetic energy
• -Or the energy due to motion from one location
to another
• A body moving in a straight line path is said to
exhibit translational motion. Therefore, the
kinetic energy of a body by virtue of its motion
along a straight path is called translational
kinetic energy.
• Example: A person walking on the road, a freely
falling object, a ball rolling on the floor, etc.,
possess translational energy.

32. Kinetic Energy
• Motion energy: It is the energy of any object in motion
including wind and water waves.
• Sound energy: Sound is produced when a substance
vibrates on application of force. Sound travels
through a medium through waves and therefore has
motion associated with it.
• Radiant energy: Electromagnetic energy including
light and solar energy moves in the form of waves.
Solar energy provides light and warmth.
• Thermal energy: It is due to the vibration and
movement of the atoms and molecules in a
substance

33. • Where KE is the energy in joules, m is
the mass in kilograms, and v is the
magnitude of velocity in meter per
second
• Since mass is never negative and v2 will
always yield a positive result, a body’s
kinetic energy has only two possible
values: zero and positive. Kinetic energy
is zero when object is not moving and
positive when the object is moving

34. The KE of an object depends on its mass and
velocity.
What will happen to the KE of an object if its mass
is doubled but the velocity remains the same?
The KE will be doubled.
How about if the velocity is doubled but the mass
remains the same?
The KE is proportional to the square of the speed,
thus if the speed is doubled, the KE will be
quadrupled

35. Potential energy
• Chemical Energy: Energy present in the bonds
between atoms and molecules.
• Mechanical energy: Energy form stored in
objects due to tension (elastic bands, spring).
• Nuclear energy: It is the energy that holds an
atomic nucleus together.
• Gravitational energy: Energy due to position or
height.
• Electrical energy: Energy stored in a battery.

36. Potential Energy
• The energy possessed by an object as a
result of its position is Potential energy.
• An object gains energy when raised from
the ground and loses energy when made
to fall.
• The energy gained or lost by an object is
called gravitational energy or simply
potential energy

50. Work, Energy and Power