Forces

1
Forces
Forces
and
and
Newton
Newton
2
Newton is famous for discovering the Force of
Gravity, but he also created 3 important Laws of
Motion!
3
Newtons 1st Law of Motion
An object in motion will stay in motion, and an
object at rest will stay at rest, unless acted on
by a force.
Translation Force is what starts and stops
motion!
4
Examples of Newtons 1st Law
a marble will not move unless forced.
once a marble is moving, it doesnt stop
until forced to!
5
if you dont wear your seatbelt, you have no
force to stop you when the car crashes!
since you keep moving, you fly through the
windshield! (and DIE)
6
Things dropped from a moving vehicle dont
fall straight down!
50 N
50 N
10 N
they keep moving forward until another force
stops them!
7
Special word to explain Newtons first law
INERTIA!
Inertia resistance to change in motion
(things dont want to start moving if they are
stopped, or stop moving if they are moving)
8
Newtons 2nd Law of Motion
Force mass X acceleration

x
This means that the magnitude of the force is
decided by how big and heavy an object is, and
how fast it is moving!
9
This makes sense big, heavy objects have a lot
of force. An elephant doesnt have to move fast!

• Small objects can have a lot
• of force if they are
• moving FAST.
• a bullet thrown by hand does nothing,
• but shot at high speed it can kill!

10
Newtons Third Law of Motion For every action,
there is an equal and opposite reaction.
Translation If you push, you also get pushed
back!
11
This is why we are able to jump-- when we
push the ground, it pushes back!