Grade 8 - Science: Unit 2: Activity 4: You've Got to Move It (Series Title: Grade 8 - Science: Unit 2:
Understanding Structures and Mechanisms: Systems in Action)
Forces
Newton Specialist: ___________________________________________
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Energy exists in many forms such as …
For example…
Energy can never be
In a physical system, energy…
Energy is what gets things….
Energy causes _____________ and forces _____________ or ________________________.
What form of energy created the forces? Are these pushing forces or pulling forces?
force
Hammering a nail
Pedaling a bike
Kicking a soccer ball
An explosion
The force of gravity
Magnetic force
Picking up garbage
Stretching a rubber band
What are some common forces?
Energy that created it
Pushing or pulling force
What is the relationship between energy and
force?
Force and Force Meters
Energy gets things moving. When things move, they push and pull other things. When something pushes or pulls
something else, that's called a force. When forces push and pull, they do work.
There is another way to measure forces if they are caused by gravity. If you know the mass of an object in kilograms, you
multiply it by 10 to estimate the force that object exerts as gravity pulls it down (you need to multiply by 9.81 if you want a
more exact answer). The formula is:
F(N) = mass(kg) x the acceleration caused by gravity (about 10m/s2)
Example
If your mass is 63 kg, you are pushing on the Earth with about 630 N of force. If someone wanted to lift you up, they would
have to pull you up with more than 630 N of force.
If you hold a 250 g (that's 0.250 kg) juice box in the air, that juice box is pulling down with about 2.5N of force. You have
to pull up with the same amount of force to keep it in the air.
If a 22 kg dog jumps in your lap, how much force is pushing down on your legs? How much force would you have to use
to lift the dog off? _______________________
If a 5 g leaf lands in your hand, how much force do you have to use to keep the leaf in one place in the air?
__________________________________
If a 557 kg elephant gets stuck in the mud, how much force would a lever, a pulley system, or a lifting machine need to
create to lift the elephant out? _______________________________
A.Who was Sir Isaac Newton?
B.What is a “Newton” (N)?
C.What is the difference between “weight” and “mass”?