Force, Motion, and Energy
SOL 4.2
HOW ARE OBJECTS LOCATION DESCRIBED?
The position of an object can be described by locating it relative to another
object or to the background. We use words like:
next to/beside
under
over
WHAT ARE MOTION AND SPEED?
Motion- is a measure of an object’s position over time
Motion=Movement
Speed-describes how fast an object is moving. Speed is a measure of motion.
________
miles per hour
________ miles per hour
WHAT IS THE ABILITY TO DO WORK CALLED?
Energy. The ability to work is called energy.
HOW DOES ENERGY EXIST?
Energy exists in two states.
Kinetic energy-is the energy an
object has because it is moving.
Potential energy-is energy that
is stored or waiting to be used.
It gives the object the future
ability to do work.
A rolling bowling ball has
kinetic energy because it is
moving.
A rock on a hill has potential
energy.
WHAT CAUSES AN OBJECT TO MOVE?
A force causes an object to move. A force is any push or pull that causes an
object to move.
Force
PUSH
PUSH
PULL
PULL
Force can cause an object to move, stop, or change directions.
WHAT EFFECTS FORCE?
The greater the force, the greater the change in motion will be.
Tap
Strike
WHY IS FRICTION A FORCE?
Friction is the resistance to motion created by two objects moving against each
other.
Friction is a force between surfaces that slows objects down or stops them from
moving.
The force that makes an object stop is called friction. Friction works against
motion. The surface of the object and what it rubs against it slows the object
and stops it from moving.
How much friction there is depends on the two objects involved.
If you push a cardboard box along a
sidewalk, there is a lot of fiction. The
smooth surface of the box is hard to
push along the rough surface of the
sidewalk.
You can easily ice skate across an icy
surface. Both the skate and the ice
have smooth surfaces, so they cause
less friction and motion is easier.
IF THERE IS NO FRICTION WILL AN OBJECT IN MOTION
EVER STOP MOVING?
Nope, it will continue moving forever. Kinda of neat huh?
IF AN OBJECT IS AT REST WILL IT MOVE WITHOUT A FORCE
APPLIED TO IT?
Nope, it will stay there forever or until a force acts upon it. Makes sense.
So remember, unless acted on by a force (like friction) an object in motion will
stay in motion and an object at rest will stay at rest until a force acts on it (like
a push or pull).
HOW DO WE DESCRIBE AN OBJECTS MOTION?
Objects move in these directions:
up
down
forward
backward
sideways