Motion
What is motion anyway?
• Motion is a change in position, which is
measured by distance and time.
• Anything moving is in motion
Developed by the Texas Education Service Center Curriculum Collaborative (TESCCC)
What changes motion?
• A force is a push or pull that can change
motion.
– A force can move an object.
– A force can transfer energy to an object.
– For example, pushing on a wall doesn’t move
the wall, but energy is being transferred.
Developed by the Texas Education Service Center Curriculum Collaborative (TESCCC)
Unbalanced Forces
• In order for a force to move an
object, there must be
unbalanced forces.
• Like tug of war…the winners are
pulling the other team with more
force; therefore, the pulling forces
are unbalanced.
Developed by the Texas Education Service Center Curriculum Collaborative (TESCCC)
http://commons.wikimedia.org/wiki/Fi
le:Tug_of_war_2.jpg
How can unbalanced forces
affect objects?
• Unbalanced forces can change the position, speed, or
direction of an object.
• Resistance forces (friction or wind) that oppose motion
can slow down an object.
• A force in the same direction can cause an object to
speed up.
• A force from a different direction can change the object’s
direction.
Developed by the Texas Education Service Center Curriculum Collaborative (TESCCC)
Balanced Forces
• If we have unbalanced forces, then there
must be balanced forces.
• When forces are balanced, an object’s
motion will be constant. It will not
change speed or direction.
Developed by the Texas Education Service Center Curriculum Collaborative (TESCCC)
Speed
• We talk about speed everyday.
• Speed is the distance traveled by a moving
object per unit of time.
• Speed affects the energy of an object. The faster
it moves, the more kinetic energy it has.
• Speed = distance
time
Developed by the Texas Education Service Center Curriculum Collaborative (TESCCC)
Calculating Speed
• If I traveled 30 meters in 10 seconds, what
was my speed?
o S = D/T
o 30m/10s
o 3 m/s
Developed by the Texas Education Service Center Curriculum Collaborative (TESCCC)
Kinetic Energy
• The energy of motion
• Objects in motion have kinetic
energy.
Developed by the Texas Education Service Center Curriculum Collaborative (TESCCC)
Distance
• Distance is a description of how far an
object traveled between two points.
Developed by the Texas Education Service Center Curriculum Collaborative (TESCCC)
Velocity
• Velocity and speed are like fraternal
twins- very similar, but with important
differences.
• Velocity is speed in a given direction.
– 35 mph NORTH
– 4 km/sec EAST
Developed by the Texas Education Service Center Curriculum Collaborative (TESCCC)
Which is which?
•
•
•
•
100 m/s right
1500 km/s
65 m/s north
3000 km/s
Developed by the Texas Education Service Center Curriculum Collaborative (TESCCC)
Velocity
Speed
Velocity
Speed
Acceleration
• Acceleration is the change in velocity.
• It can be a change in speed, direction, or
both.
Developed by the Texas Education Service Center Curriculum Collaborative (TESCCC)
Friction
• Friction is a force that opposes motion.
• It can be caused by wind, water, surface
texture, etc.
• Have you ever ridden down the street on
your bike and felt the wind push against
you?
• That’s air resistance!
Developed by the Texas Education Service Center Curriculum Collaborative (TESCCC)