Download the File

Chapter 6
Forces and Motion
Lesson I
I.
What is Motion?
A. When you want to know where something is you want to
know its position. (location)
1. How you describe the position of an object depends
on where you are.
B. Motion is simply changing position.
1. When you describe motion part of your description
depends on your position.
2. You can vary your motion from fast to slow.
C. Average Speed is the distance you moved by the time it
took you to move that distance.
1. Average speed = total distance ÷ total time
D. Velocity describes both your speed in a given direction.
1. For two things to have the same velocity they must
be traveling at the same speed and direction.
Chapter 6
Forces and Motion
Lesson 2
I. Forces in your world
A. Forces are at work when: you push a button, your
dog pulls on a toy, or the wind pushing your kite.
B. You use forces and forces act on you at work and at
play.
C. Forces are all around you.
D. Forces can act together (Balanced Force) or against
each other (Opposing Forces).
E. Forces can hold objects together or keep them apart.
Ex. Magnetism, gravity
F. Forces are needed to start, stop, or change any
motion.
G. A force is a push or pull one body exerts on another.
H. Force = Mass x Acceleration
II.
Force of Gravity
A. The force of gravity is the pulling force of every
object on every other object.
B. You can’t see the force of gravity but you can see
what it does.
1. The force of gravity affects all objects, because
all objects have mass.
III. Friction
A. Friction is a force that slows down and stops moving
objects.
1. Friction occurs when two objects move across each
other.
2. Different surfaces result in different amounts of
friction.
3. Friction can be very useful it allows you to start and
stop moving. If there was no friction you wouldn’t
be able to stand at all. (ice)
4. Friction can cause a problem when moving parts get
worn away and need to be replaced. (machines) (oil
is a lubricant)
5. Covering parts with oil creates less friction.
IV. Forces and Pressure
A. Pressure is a measure of the amount of force applied to a
given area.
1. Solids, liquids, and gases all apply pressure.
Chapter 6
Forces and Motion
Lesson 3
I. Newton’s Laws of Motion
A. Balanced means the two teams’ forces are equal in size,
and they are pulling in opposite directions.
1. Without any unbalanced force acting on an object,
there is never any change in its motion.
B. Isaac Newton made many important discoveries about
position, motion, and forces.
1. Today these laws are still important.
II. First Law of Motion.
A. The first law of motion states: (INERTIA)
1. That objects at rest stay at rest
2. Objects moving in a straight line will stay in motion
in a straight line and at the same speed unless acted
on by an unbalanced force.
II. Second Law of Motion
A. Acceleration is any change in the speed or direction or an
object.
B. Second Law of Motion states that objects acceleration
depends on the size and direction of the forces acting on
it and on the mass of the object.
1. Example friends helping you (size) push a wagon
full of bricks (mass) compared to pushing the wagon
alone (size) and empty (mass).
III. Third Law of Motion
A. Third law of motion states that for every force there is an
equal and opposite reaction force.
B. Pairs of action are called action – reaction forces.
1. Example. Girl on roller skates pushes on wall, wall
pushes back. Getting out of a boat. Push on boat,
boat pushes back.
C. Law of conservation of momentum – states that
momentum is not lost only transferred.
Ex. Pool ball hits another ball. Other ball moves
with equivalent momentum
D. Newton was the first to write down the laws and show
proof. His work still helps scientific study today.