Transcript Newton`s Third Law.

Unit B, Chapter 4,Lesson 5
Action and Reaction
• Newton’s third law states that when one object
exerts a force on another object, the second
object exerts an equal force and moves in the
opposite direction.
– Example: A frog jumping off a Lilly pad.
• All forces come in pairs.
– They are called action and reaction forces.
– If you push down on your desk, or lean against a
wall, the desk and the wall push against you with an
equal force.
• Forces must be balanced whenever an object is
at rest.
Action and Reaction
•
People who design rockets use
Newton’s Third Law.
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•
For example, the gases that are in a rocket’s
engine push backward and makes the
rocket go up.
When you walk it is also an example
of action and reaction.
– When you push your foot on the ground the
ground pushes back with equal force.
– Since you push your foot off the ground, it
makes you move forward.
Newton’s Laws at the
Amusement Park
• Motion, gravity, mass, forces,
acceleration, friction, inertia, and
reaction, are all important parts of
amusement park rides.
– An example of the first law is a roller coaster
and the swings.
• If you didn’t have straps on a roller coaster you
would fall out and get seriously injured.
• When the swings start moving in a circular
motion, you would fly out of your seat. It wouldn’t
be pleasant!
Newton’s Laws at the
Amusement Park
– Another example of the second law is hitting a
target with enough force to make the bell ring.
It tests your strength.
– An example of a ride using Newton’s third law
is bumper cars. When they hit, they bounce
backward with an equal force.
– Newton’s law can be displayed in all different
rides. Next time your on a ride, think about
what law might be demonstrated.