INERTIA An object will remain at rest or in constant motion unless acted upon by an unbalanced...
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Transcript of INERTIA An object will remain at rest or in constant motion unless acted upon by an unbalanced...
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”
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 stop
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 cup
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
spin
Why? The liquids inside the
egg were in motion & wanted to stay in motion due to inertia
Cups & Paper Towel
Which 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 inertia
Think, Pair, Share1.) 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?
Vectors- arrows that show the direction & strength (magnitude) of a force
•Longer Arrow = Stronger Force•Shorter Arrow = Weaker Force•Forces measured in Newtons (N)
Balanced Forces- equal in strength & opposite in direction
Cancel each other out so net force = O
Results in NO MOTION or NO CHANGE in motion
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.
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/s2
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 massive
More Distance = Less gravity
Acceleration due to Gravity = 9.8 m/s2