Transcript Forces PowerPoint

Forces
SOL 4.2
(Information Used from www.solpass.org)
Force
• A force is a push or a pull. Every time you
push or pull something you use a force.
Forces transfer energy.
Energy
• When you throw a ball, the force of your arm
pushes the ball into the air. Energy is
transferred from your arm to the ball.
Potential Energy
• Stored energy
• Energy on hold and
ready to go
Push and Pull
• A pull that starts an
object moving might
be the pull of gravity
or the pull of a
magnet. A push that
starts an object
moving might come
from the wind or the
muscles in your legs.
• Once it is moving it
has kinetic energy.
Inertia
• An object in motion will stay in motion,
until a force stops it. The force
stopping the object's motion might be
an obvious one - the ground!
• An object at rest will stay at rest, until a
force starts it moving.
Friction
• A less obvious force that
stops or slows motion is
friction. Even air causes
friction. Friction is a force
that prevents or stops
motion. Friction is the
resistance to motion
created by two objects
moving against each other
(the sled and the snow).
Friction creates heat. (rub
your hands together)
Mass and Inertia
• How a force affects an object depends
on the object's mass. The more
massive an object, the less effect a
given force will have on the object.
More massive objects are said to have
more "inertia".
Quiz Time #1
• Which shoe tread would provide the most
friction to keep you from slipping?
– A.
--C.
– B.
--D.
Correct Answer-A
Quiz Time #2
• Objects in motion have ______________
energy.
– A.
– B.
– C.
– D.
Stored
Kinetic
Potential
Negative
Correct Answer-B
Quiz Time #3
• Due to the pull of gravity, the higher an
object is off the ground, the more
_________________ energy it has.
– A.
– B.
– C.
– D.
Kinetic
Electrical
Chemical
Potential
Correct Answer-D
Quiz Time #4
• When an apple is hanging on a tree it has
potential energy. When it falls off the tree,
potential energy changes to:
– A.
– B.
– C.
– D.
Chemical Energy
Kinetic Energy
Nothing
Electrical Energy
Correct Answer-B
Quiz Time #5
• In order to move a
piano that weighs 800
pounds, you will have
to produce more or
less force than
moving a piano that
weighs 400 pounds.
800 lbs
400 lbs
Correct Answer-more force
Quiz Time #6
• You are having a hard time getting a ring
off of your finger. What could you do to
reduce the amount of friction to help you
remove the ring?
– A.
– B.
– C.
– D.
Rub the ring with a cloth
Have a friend pull as hard as they can
Put baby powder on the ring
Put oil on the ring
Correct Answer-D