Force and Motion
A LOOK AT THE NATURE OF ENERGY
What is Force?
 A force is a push or pull.
 A force may give energy to an object, creating
motion, stopping motion, or changing its direction.
 Balanced forces are opposite in direction and equal
in size. When forces are balanced, there is no change
in motion.
 Unbalanced forces cause a change in motion.
Balanced and Unbalanced Forces
Friction
 Friction is a force that opposes motion.
 The three kinds of friction are sliding, rolling, and
fluid friction.
Gravity
 Gravity is a force of attraction that exists between all
objects in the universe.
 The size of the force of gravity depends on the
masses of the two objects and the distance between
them.
Impact of Mass on Gravity
 The size of the gravitational
pull between objects
depends on the masses of
the objects.
 The larger the mass, the
greater the gravitational
pull.
 Even our own bodies have
gravity. The Earth's gravity
is far stronger than our own
so we don't notice the
gravity our bodies possess.
Nature of Energy
 Energy is the ability to do work.
 Energy can appear in many forms:
 Mechanical
 Heat
 Chemical
 Electromagnetic
 Nuclear
Potential Energy
 Energy that an object has due to its shape or position
is called potential energy.
 The potential energy that an object has is due to its
height above the Earth’s surface.
Kinetic Energy
 Energy that an object has due to its motion is called
kinetic energy.
 The heavier a thing is and the faster it moves the
more kinetic energy it has.
Potential and Kinetic Energy Examples
Law of Conservation of Energy
 The law of conservation of energy states that energy
can neither be created nor destroyed by ordinary
means.
When we use energy,
it doesn’t disappear.
We change it from one
form of energy into
another.
Measuring Motion
 Motion involves a change in position during a certain
amount of time.
 The rate at which an object moves is speed. Any
object that is changing its position has speed.
 Speed that does not change is called constant speed.
Velocity and Acceleration
 Speed only describes how fast an object is moving,
whereas velocity gives both how fast and in what
direction the object is moving.
 Acceleration is the rate of change in velocity.
 An object speed up is positive acceleration.
 An object slowing down is negative deceleration.
Momentum
 Momentum describes how strong a moving thing is.
 Things that aren't moving have no momentum.
 Moving things have less momentum if they are light
or moving slowly, and more momentum if they are
heavy or moving fast.
Force and Motion Games/Websites
 http://www.gamequarium.com/forcesandmotion.html
 http://phet.colorado.edu/en/simulation/forces-and-motion-basics
 http://www.bbc.co.uk/schools/scienceclips/ages/6_7/forces_movement.shtml
 http://sciencegames.4you4free.com/force_motion_gravity.html
 http://studyjams.scholastic.com/studyjams/jams/science/forces-and-
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motion/force-and-motion.htm
http://studyjams.scholastic.com/studyjams/jams/science/forces-andmotion/fgravity-and-inertia.htm
http://studyjams.scholastic.com/studyjams/jams/science/forces-andmotion/inertia.htm
http://studyjams.scholastic.com/studyjams/jams/science/forces-andmotion/acceleration.htm
http://studyjams.scholastic.com/studyjams/jams/science/forces-andmotion/action-and-reaction.htm