Jarmoluk (pixabay.com)
Newton’s 3rd Law
Action
Reaction
Action
Reaction
Newton’s 3rd Law
(of motion)
(of motion)
I can . . .
For every ACTION there is an opposite and equal REACTION.
If A pulls B (left),�B pulls A (right).
A
B
Clifton Bluhm
Which force accelerates the car to the right?
Clifton Bluhm
http://www.soccer-shots.com/GMU2003/gmu-030928-x-115.jpg
Which received a LARGER force, the foot or the ball?
ACTION = Earth Pulls Astronaut DOWN
REACTION = Astronaut Pulls Earth UP
MEarth = 5.976 x 1024 kg
MAstronaut = 71.4 kg
FAstronaut = 700 N� (157 lbs)
FEarth = ?
AAstronaut = 9.8 m/s2
AEarth = ?
700 N
10,000 people
.
Entire Population of Earth = 7.0 billion
= 7.0 x 109
.
Astronaut weighs 700 N
30 kg
10 kg
30 kg
10 kg
Acceleration UP = +2.0 m/s2
Use, g = 10 m/s2.
Blue
Red
From Blue = ?
From Earth = ?
From Earth = ?
From Red = ?
From Floor = ?
120 N
100 N
300 N
120 N
480 N
agun =
abullet
f
f�mbullet
mgun
=
Which received the LARGER force?
BOTH received the SAME force!
Which experienced the LARGER acceleration?
The one with the SMALLER mass!
Which person received a LARGER force?
https://www.mcbhawaii.marines.mil/News/News-Article-Display/Article/540200/martial-arts-instructor-course-to-begin-march-24/
Flavio~
It is IMPOSSIBLE for someone to hit the paper with 50.0 lbs of force!
Force = 50.0 lbs� = (223 N)
masspaper = 4.45 g� = (.00445 kg)
accel = 50,100 m/s2
(5,010 “g’s”)
The paper is not capable of pushing BACK with 50 lbs.
Newton’s 2nd Law:
Newton’s 3rd Law:
Reaction
Reaction
ACTION / REACTION FORCES�DON’T CANCEL
Action
Action
ACTION / REACTION FORCES�DON’T CANCEL
http://www.intermath-uga.gatech.edu/dictnary/images/circle/cart.jpg
20 N, Cart ON GROUND
300 N, Ground ON HORSE
100 N, Horse ON CART
? N, Cart ON HORSE
? N, Net Force ON HORSE
? N, Net Force ON CART
? N, Horse ON GROUND
? N, Net Force�ON HORSE/CART SYSTEM
? N, Ground ON CART
http://www.intermath-uga.gatech.edu/dictnary/images/circle/cart.jpg
50 N, Cart ON GROUND
100 N, Horse ON CART
? N, Net Force ON CART
300 N, Horse ON GROUND
? N, Net Force�ON HORSE/CART SYSTEM
50 N, Ground ON CART
300 N, Ground ON HORSE
100 N, Cart ON HORSE
? N, Net Force ON HORSE
200 N
? N, Net Force�ON HORSE/CART SYSTEM
? N, Net Force ON CART
50 N, Ground ON CART
100 N, Horse ON CART
200 N
50 N
How does the mass of the horse compare to the mass of the cart?
250 N
50 N, Ground ON CART
300 N, Ground ON HORSE
? N, Net Force�ON HORSE/CART SYSTEM