October 11, 2011
Objective: Review Chapter 3 Concepts
BW- Define Newton's Third Law
BW: Solve the following problems
1. What is the momentum of a 100kg football player running at a speed of 4m/s?
- Hand in Bellwork sheet
-finish 3.3 notes
• Review worksheet- groups work through on board
· Video
• Wksh (37/38)
Demo Newton's Cradle with lab
- Turn in bullseye lab
- Go over math worksheet
- 3.3 notes
-Pendullum lab
Homework:
• Page 94 #1-18
-All summaries due next class
Homeworkwkst 21/29
3-3 notes
action there is an equal but
I. Newton's 3rd law of motion- for every ______
opposite _________
reaction
II. Momentum - related to how much force is needed to change an
objects motion. Has mass and speed.
Inertia?form. p = m x v
ex. for every push, something pushes back
units? p=kg•m/s m= kg v= m/s
a. action /reaction with swimmer
example of high “p” objects
Action- swimmers hand pushes water.
Reaction- water pushes swimmer forward
c. Rocket Propulsion
1. how works?
A. How does a 175 lb db stop a 250 lb full back?
Gas
pushes
rocket up
fireextinguisher cart.mov
m
B.
a. Action-Rocket pushes out hot gases
b. Reaction-Many hot gases push back on rocket
V
=
M
v
A ball of 6 kg travels at 2 m/s. what is it's "p"?
Rocket
pushes out
gas
C. A ball of 2 kg traveling at 8 m/s. What is p?
D. They collide head on Where will they go?
2kg
6kg
October 11, 2011
III. Force and changing momentum
A. When the momentum changes on an object a force is applied.
ex.- your hand feels a force when you stop the a baseball
IV. Law of conservation of momentum - the total momentum of a
system of objects does not change, it can be transfered.
ex. shooting a billard ball with high velocity will cause many balls
to move at a slower velocity
formula- F = (mvf - mvi)
t
do applying math number 7
form.
m1v1 = m2v2
prob- A 50 kg clown is shot out of a cannon at 20 m/s. What is
the recoil speed of the cannon if its mass is 250 kg?
p(clown)
cannon recoil.mov
m • v
=
p(cannon)
m
• V