Download Motion and Design Notes Miss Calfe Name I. Force – a push or a

Motion and Design Notes
Miss Calfe
Name ___________________________________
I.
Force – a push or a pull
Balanced forces: two equal forces pushing or pulling in opposite directions.
Example: our K’Nex car didn’t move when there were only 2 small washers
because the forces were balanced.
Unbalanced forces: two forces pushing or pulling in opposite directions with one
force stronger than the other.
Example: our K’Nex car moved when we added one large washer to our
paper clip because the force of gravity was the stronger force.
II. First Law of Motion
An object in motion will want to stay in motion, and an object at rest will want to stay
at rest.
A force is needed to get an object moving, stop an object, or change direction.
Inertia – a property that states an object wants to keep moving or stay still, and that
you need a force to change what something is doing.
Examples:
Our K’nex car stayed at rest when there were no washers on the paper clip
because it was already at rest and there was no force to change that.
Our K’nex car kept moving even after the washers hit the floor because it was
already in motion.
Motion and Design Notes
III.
Miss Calfe
Second Law of Motion
The heavier an object is, the more force you need to keep it moving, stop it, or get it to
go faster.
Acceleration – to go faster
Force = mass x acceleration (F = MA)
Examples:
When we added 2 blocks to our car and kept the washers the same, it move
slower because we added mass.
To make our car go faster with 2 blocks, we would need more washers (force).
IV. Types of Energy
Kinetic Energy – the energy of motion
Examples
When we wind the rubber band around our car’s axle and let the axle
go, the wheels begin to spin. At this point, we would call the energy
kinetic because the car is moving.
Potential Energy – stored energy
Examples
When we wind the rubber band around the axle, we are storing
energy. This is called potential energy because we have stored the
energy in the rubber band so the car as the potential to move, but its
not moving yet.
Motion and Design Notes
Miss Calfe
II. Friction – the force that opposes motion

Air resistance – friction created when air hits a vehicle.

Drag – another name for air resistance.

Aerodynamic – designs that get rid of or decrease air resistance.
ADD FRICTION
 Tires (+)
 Cleats (+)
 Chalk on hands (gymnastics,
softball) (+)
 Tan connectors on the outside (-)
 Propeller hitting the vehicle while
it spins (-)
REDUCE FRICTION
 Tan connectors on the inside (+)
 Crossbars (+)
 Wax on skis (+)
 No tires (-)
II. Third Law of Motion – every action has an equal and opposite reaction
Examples:
 When your propeller spins, it pushes air behind it. In an equal and opposite
reaction, the air pushes back on the propeller, causing your car to move
forward.

Soccer ball: when you kick a soccer ball, the ball pushes back on your foot
with an equal amount of force. This is why you feel the ball when you kick it.
Because the ball has way less mass than you, the force is strong enough to
make the ball move, but not you.
III. Types of Energy

Potential energy – stored energy

Kinetic energy – energy of motion
POTENTIAL ENERGY
 Winding the rubber band around
the axle
KINETIC ENERGY
 Letting go of the axle/rubber
band and the axle spins