Transcript Science Benchmark 3 Review

Science Benchmark
3 Review
Motion, Laws of Motion,
Machines, Work, Power,
Energy, Energy
Transformations
Motion
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In order for there to be motion
an object must move in relation to
reference points
Speed
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How much time it takes for an object to
move a certain distance
Formula
v= d/t
Measured in m/s or km/hr etc
If you know both speed and direction then
you know ----
 Velocity
Acceleration
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The RATE at which velocity CHANGES
All these are acceleration :
Going faster
Going slower
Turning

This is why planets are accelerating – they
are in a constant turn to form their orbit.
Laws of Motion
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1st - inertia – objects want to keep doing
what ever they are doing
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Books fly on floor when bus stops
You move forward when your parents slam on
the car brakes
Laws of Motion
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2nd – acceleration – f=ma
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A runner speeds up at the end of a race
A car slows down because they ran out of gas
It takes more force to stop a bus than a
bicycle
To change acceleration – lower mass or use
more force
Laws of Motion
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Remember :
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Mass is the amount of matter in an object
Weight is a measure of the pull of gravity on
an object
Laws of Motion
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3rd – action and reaction – equal and
opposite!!
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When you jump down hard on a trampoline
you will go high in the air
When a rocket is fired the gases push
downward causing the rocket to go upward
Machines
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There are six simple machines:
1. Lever
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1st class
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2nd class

3rd class
Machines
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2. wheel and axle
 3.
Machines
wedge
 4.
Machines
screw
 5.
Machines
inclined plane
 6.
Machines
pulley
Work

Work is using a force to move an
object in the direction of the force
Formula w=fd
 Measured in joules (J)
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Power
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How much work is done in a certain
period of time.
The faster something does work the more
power it has!! (less time)
Formula P=w/t
Measured in watts (w)
Energy
 Energy
is the ability to do work
or to make a change.
 There are two main categories
of energy:
 Potential
 Kinetic
Potential Energy
 Potential
energy.

Food
Energy is stored
roller coaster
Kinetic Energy
 Kinetic
motion
Energy is energy of
Energy
Transformations
 Energy
is changed from one
form to another but none can
be created or destroyed!
Match – chemical
to thermal
Energy
Transformations
Food – chemical
to mechanical
Energy
Transformations
Food – chemical
to mechanical
Chemical Reactions
Remember the only true proof that a
chemical reaction has taken place is
the formation of a new
substance with new
properties!!!
Chemical Formula
2Ca + O2
Reactants
2CaO
Product
Remember to count atoms to
see if balanced!
Good Luck!!!!
Read well !!!!