Newton’s 1st Law
The first law of motion sates that an
object will not change its speed or
direction unless an unbalanced force (a
force which is distant from the reference
point) affects it. Another name for the
first law of motion is the law of inertia. If
balanced forces act on an object it
doesn’t accelerate or change direction.
This means it doesn’t change its velocity
and it doesn’t have momentum.
Examples of Newton’s 1st
If you slide a hockey puck on ice, eventually it will stop,
because of friction on the ice. It will also stop if it hits
something, like a player’s stick or a goalpost.
If you kicked a ball in space, it would keep going
forever, because there is no gravity, friction or air
resistance going against it. It will only stop going in one
direction if it hits something like a meteorite or reaches
the gravity field of another planet.
If you are driving in your car at a very high speed and
hit something, like a brick wall or a tree, the car will
come to an instant stop, but you will keep moving
forward. This is why cars have airbags, to protect you
from smashing into the windscreen.
Newton’s 2nd Law
The second law of motion states that
acceleration is produced when an
unbalanced force acts on an object
(mass). The more mass the object has
the more net force has to be used to
Examples of Newton’s 2nd Law
If you use the same force to push a
truck and push a car, the car will have
more acceleration than the truck,
because the car has less mass.
It is easier to push an empty shopping
cart than a full one, because the full
shopping cart has more mass than the
empty one. This means that more force
is required to push the full shopping cart.
Newton’s 3rd Law
The third law of motion sates that for every
action there is a an equal and opposite
reaction that acts with the same
momentum and the opposite velocity.
Examples of Newton’s 3rd
When you jump off a small rowing boat into water,
you will push yourself forward towards the water.
The same force you used to push forward will
make the boat move backwards.
When air rushes out of a balloon, the opposite
reaction is that the balloon flies up.
When you dive off of a diving board, you push
down on the springboard. The board springs back
and forces you into the air.