1 st Law of Motion Inertia An object will remain at rest or in constant motion unless acted upon by an unbalanced force The Old Tablecloth Trick How does this comic relate to Inertia ID: 655477
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Slide1
Newton’s Laws of MotionSlide2
1st
Law of Motion
Inertia
An object will remain at rest or in constant motion unless acted upon by an unbalanced force.
“The Old Tablecloth Trick”Slide3
How does this comic relate to Inertia? Slide4
Mass- the amount of “stuff” or matter in an object
Which has more mass?
Which has more mass?Slide5
Do All Objects Have the Same Inertia?
Less Mass = Less Inertia
The skier does not have a lot of mass therefore has LESS inertia; & is easier to stop
More Mass = More Inertia
The car has MORE MASS therefore has A LOT OF INERTIA; & is harder to stopSlide6
Penny in Cup Demonstration
Finger applies a force to a card causing it to move
Penny STAYS at rest (over the cup) due to inertia
Gravity causes the penny to fall into cupSlide7
Spinning Eggs Demo
What happened to the spinning hardboiled egg when you tapped it?The egg stopped spinning
Why?
The egg is a solid unit and the finger applied enough force to change the inertia
What happened to the spinning raw egg when you tapped it & let go?
The egg continued to spinWhy?The liquids inside the egg were in motion & wanted to stay in motion due to inertiaSlide8
Cups & Paper TowelWhich cup was easier to keep standing?
The cup (more massive one) because it has more inertia
The empty cup was harder to keep standing because it has less mass therefore less inertiaSlide9
Think, Pair, Share
1.) What will happen to the bone or stick if the forces acting on it are not equal?
2.) What direction will the bone or stick move?Slide10
“Bullies in a Box” showing Newton’s Laws of MotionSlide11
Vectors- arrows that show the direction & strength (magnitude) of a force
Longer
Arrow = Stronger Force
Shorter Arrow = Weaker Force
Forces measured in Newtons (N)Slide12
Balanced Forces- equal in strength & opposite in direction
Cancel each other out so net force = O
Results in NO MOTION or NO CHANGE in motionSlide13
Unbalanced Forces
Forces that don’t cancel & the object moves in the direction of the stronger force.
DIFFERENT directions, SUBTRACT the forces
SAME direction, ADD the forces. Slide14
Practice finding the Net Force…Slide15
Determining the Net Force…Slide16
2nd
Law
F= ma
An object acted on by an unbalanced force accelerated in the direction of the forceSlide17
F=ma???? What does it mean?
Force= mass x
acceleration
Mass (kg or grams)
Acceleration (m/s2)1 Newton= force needed to move 1 kg 1 m/s
2Slide18
Gravity-force of attraction between objects; depends on mass & distance between them
More Mass = More Gravity
Earth has more gravity than Moon
b/c
Earth is more massiveMore Distance = Less gravity
Acceleration due to Gravity = 9.8 m/s2Slide19
Mass vs. Weight…What’s the Difference?