Download What is Force?

What is Force?
MR. MCMARTIN
BETA POD SCIENCE
Interesting Fact
 Basic Forces of Nature
 Scientists have found evidence that the interactions of only
four basic forces can describe all physical properties and
relationships in nature. These forces are:
The gravitational force, which acts on all matter (which has mass)
and on light (which has no mass).
 The electromagnetic force, which is responsible for the attraction
and repulsion of all kinds of matter that have electric or magnetic
properties.
 The strong nuclear force, which binds the protons and neutrons of
atoms together in the nucleus.
 The weak nuclear force, which describes some interactions
between subatomic particles.

Force and Measurement
 Force: a push or a pull
 A force can change acceleration of an object.
Acceleration can be change in speed or direction
 Anytime you see a change in motion of an object you can be sure it
was created by a force.

 Force is expressed (or labeled) in units called
Newtons.
 Newton: the SI unit for force.
True statements
 All forces act on objects. For any push to occur,
something has to receive the push. The same is true
for any pull.
 Just because force acts on an object doesn’t mean
that motion will occur.

Ex. You’re sitting on a chair, but your chair doesn’t move
because the floor is pushing back up on the chair.
Unseen Sources and Receivers of Forces
 It’s not always easy to tell what is exerting a force or
what is receiving a force.

Ex. Magnets and Gravity
Determining Net Force
 Usually, more than one force is acting on an object.
 Net force: the combination of all forces acting on an
object.
 To determine the net force you must first determine
the direction of the forces.


Forces in the same direction: add the forces
Forces in opposite directions: subtract the smaller force from
the larger force. The direction would then go towards the
larger force.
Balanced and Unbalanced Forces
 If you know the net force on an object, you can determine the
effect of the net force on the object’s motion.

The net force tells you if the forces are balanced or unbalanced.
 Balanced force: When the forces on an object produce a net
force of 0 N.

Most forces around you are balanced. They need to be in order to stay in
place. Ex. Walls around you.
 Unbalanced force: When the net force on an object is not 0 N.




Produce change in motion
Cause a non moving object to start moving
Change in motion of a moving object which changes it’s direction and
speed
Objects can continue to move after unbalanced forces are removed. Ex. A
pool ball continues to roll after being hit by the pool stick.