Download Forces Chapter 10 Mrs. Yakulis 8th Grade

Forces
Chapter 10
Mrs. Yakulis
8th Grade
Name__________________
Section 1 Nature of Forces
Force is a _____________
Has _______________ (size)
Measured in ________________ (after Isaac Newton)
Does not have to result in motion if __________________
Magnetism, electricity and gravity all exert forces that we cannot see
Combination of forces is called ______________
Forces in the same direction _________________
Forces in different directions _________________________
The _______________ always acts in the direction of the ______________
If net force is not zero, force is __________________________
If net force is zero, force is balanced____________________________
Unbalanced forces are needed to change _________________ (direction and speed of an
object)
Balanced forces do not __________________________________
Section 2 Friction, Gravity and Elastic Force
Friction: Force that _________________________ that are touching
Amount of friction is determined by _________________ (rougher, more friction) and
___________________ (greater force, more friction)
Types of friction
______________
_________________ (wheels, ball bearings)
_____________________ (gases and liquids)
______________________ (balanced forces, no movement until force applied)
Reduce: make surface smoother, use lubricants, ______________________
Increase: make surfaces rougher, _______________________________
Gravity
Force of attraction of objects (pull) due to ________________________________
Matter has mass:
Amount of _____________________
SI unit is _____________________
Is also a measure ______________________:
 Tendency of an object to _______________ in motion
Large mass, more inertia (_______________________)
Weight:
____________________ from mass
Measure of _______________________
Force of attraction due to mass (pull)
SI unit for force is ___________________
1N= ________________________
Measured with a ______________________________
Weight = mass x _________________________
1Newton= kg x m/s2
Weight will vary at other places in ________________________
Isaac Newton noticed the same force for a falling apple as
_________________________________________________________
Law of Universal Gravitation
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Formula:
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G is a constant, m1 is mass of first object, m2 is mass of second object and r is distance between
them
•All objects fall at the same ______________________• ___________________ leaning tower of Pisa
• Dropped cannonballs of ________________
• Land at ___________________________
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A___________________________________ TO PRODUCE THE SAME ACCELERATION
F=_______________
A=F/M
•
All objects accelerate towards Earth at a rate __________________
•Air resistance slows down ____________________
• ___________________also known as air resistance
• Depends on _____________________ of object
•Acceleration stops at ______________________________
• As objects fall, air resistance increases until ________________________________
• Object continues to fall, but at a constant ________________________________
•
___________________ (acceleration due to gravity) means that object is falling with
____________________ (such as air resistance) acting on it except ______________
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Astronauts appear to be __________________ due to “freefall” in orbiting spacecraft
________________________ = traveling in circular path
_______________________________ combine to form an orbit
This is an _________________ force because it changes the __________of an object
Centripetal Force
•_____________ = unbalanced force which causes __________ motion (__________ provides this
force)
•Centripetal means ______________________•____________ is an example of __________________
• Curved path when horizontal velocity combines with vertical acceleration
• Examples:
(gravity)
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___________Hopping ___________________
Water sprayed _____________________
Momentum
• A property that depends on _____________________
• More momentum, harder to ________________________
• Mass * velocity
• ____________________
•Law of _________________ of momentum
• Momentum is ______________________
• __________________ forces are equal and opposite
• Billard balls
• Bowling
•Compression force- elastic ____________________ matter together
• _________________- elastic force that stretches or pulls matter