|
|
|
Physics 40 |
|
Chapter 7-Momentum |
|
|
|
|
|
A juggler tosses a ball upward just as a ball in
the air reaches the top of its arc. The acceleration of the ball in the
hand is upward. |
|
The acceleration of the ball in the air is |
|
downward |
|
upward |
|
zero |
|
|
|
|
|
Ball in the hand |
|
Does it have weight |
|
Unbalanced Force? |
|
Ball at the top |
|
Does it have weight |
|
Unbalanced Force? |
|
F = ma |
|
|
|
|
|
Impulse and momentum |
|
Newton and his 2nd law |
|
Sports |
|
|
|
Conservation of momentum |
|
Immortality and invariance |
|
Rocket Science |
|
Bootstrap machines |
|
|
|
|
|
Galileo’s impedo |
|
Proportionality with height or velocity? |
|
Court politics |
|
Newton’s pronouncement |
|
English impedo was velocity proportional |
|
|
|
Force proportional to rate of change |
|
|
|
|
|
|
|
Learning golf |
|
Follow through |
|
FDt=D(mv) |
|
Maximizing momentum |
|
Force is strength |
|
Time is skill |
|
FDt=D(mv) |
|
|
|
|
|
Maximizing Force |
|
Momentum is strength |
|
Time is skill |
|
FDt=D(mv) |
|
Aiming beyond |
|
Sports of hitting |
|
Using hammers |
|
|
|
|
|
Boxing |
|
Get it over with? |
|
Fading with the blow |
|
FDt=D(mv) |
|
Starting a train |
|
|
|
|
|
Judo falls |
|
Spread out to minimize pressure |
|
Slamming the floor with your arm |
|
Newton’s third law |
|
Action and reaction |
|
Force is only half the interaction |
|
Arm and body in freefall |
|
|
|
|
|
Impulse of action = Impulse of reaction |
|
If |
|
FA = FR |
|
and Dt = D t then |
|
D(mv)A= D(mv)R |
|
Always !! |
|
Transferring momentum |
|
Not always obvious |
|
The Earth comes up! |
|
|
|
|
|
Where does the momentum go? |
|
Max at bottom |
|
zero at top |
|
Isolating system |
|
|
|
|
|
|
|
(Work is next chapter) |
|
|
|
|
Gottard
and the New York Times |
|
|
|
Center of Mass of rocket and fuel |
|
|
|
|
Paul Bunion |
|
|
|
|
|
The Dean patent |
|
Spinning machines |
|
|
|
|
|
A trip along US 50 |
|
Given: |
|
20 tons |
|
|
|
Weigh |
|
More? |
|
Less? |
|
Same? |
|
|
|
|
|
|
|
|
|
|
|
Notes