Laws of Motion Section II

Laws of Motion Section II: Inertia and Force objectives
1. Explain what Newton’s Law of Action and Reaction is all about.
2. Explain how “equal but opposite” forces do not have “equal and opposite” results in motion-changes.
Inertia and Force Reminder
--Remember, according to the Law of Inertia, the ___________________ an object has, the ________________ it has.
--_________ itself is a _____________ against all forces trying to _______________________—whether it is standing
still, or already in motion.
--Newton’s 3rd Law applies to __________, and ________________________ by other objects or forces.
Newton’s Law of Action and Reaction
“For every _________ acted on an object, there is always an _________________
____________ Force from the object.”
--So every time a _________ is applied to one object, the 2nd object will
_____________________________ as the first.
Example 1; Bottle rocket
1. Action Force—______________ explosion that _____________ of the rocket
2. Reaction Force—______________ in the opposite direction as the flame-out.
Example 2: Hammer-strength game
1. Action—_________ a springboard ____________ with a hammer.
2. Reaction--the springboard ______________ with equal force as the force from the hammer.
Effects of Inertia and the law of Action/Reaction
--Each of the 2 objects involved with ____________________
ALWAYS ________________________, but almost never
change their motion equally!!!
This is because of their ______________!!
Example: Revolver (.45 cal) vs Handgun (.45 cal)
--A .45 caliber cartridge, when fired, generates about
__________________ of force to _________ the bullet.
--The __________ pushes back with the
_________________________each time (240 N).
--A handgun is ____________, with a ____________ body, and
the effect of _________ (from the same caliber) seems to be
____________________ due to a ________________ level.
--A revolver has a solid steel body, and is much ______________
than a handgun, so the _________________ due to a
________________ level
Example2 : rubber ball versus face.
1. The _______________________ is the __________________-- the force goes into the face.
2. At the same time, a _____________Force ___________________ pushes into the ball
--The ____________ of the forces applied to ______the _______ and the _____ are _________ in strength.
--The reason why the ball bounces away and the person moves a little bit is….
1. The ball’s __________________ and has only a ____________________. So, the Reaction Force is plenty strong
enough to ______________________ away.
2. The ___________ Force applied into the person’s ________ was ________________as the Reaction Force the ball got.
But, because of its _________________, the person has much _______________ than the ball, so that
_______________ has a _______________ effect.
--If __________________ had no impact on Action/Reaction Forces, then you could demolish a house with __________.
Review Questions
1. What is Newton’s 3rd Law of Motion (Action and Reaction) mean?
2. The strength of Action and Reaction is always……
3. According to the Law of Action and Reaction, if you pull out 3 balls on a Newton’s Cradle (the metal click-clacky ball
swing-thing), and it hits the 4th ball, AND THEN the 4th ball hits the other 3 balls, how many of those ball will swing out
after the 4th ball hits them?
4. Explain why doing push-ups the “push up” off the ground lifts you up, but not does seem to push the ground down.