![Page 1: Chapter 6 Momentum 1.MOMENTUM Momentum - inertia in motion Momentum = mass times velocity Units - kg m/s or sl ft/s](https://reader035.vdocuments.us/reader035/viewer/2022081511/56649d1a5503460f949ef4f7/html5/thumbnails/1.jpg)
![Page 2: Chapter 6 Momentum 1.MOMENTUM Momentum - inertia in motion Momentum = mass times velocity Units - kg m/s or sl ft/s](https://reader035.vdocuments.us/reader035/viewer/2022081511/56649d1a5503460f949ef4f7/html5/thumbnails/2.jpg)
Chapter 6
Momentum
![Page 3: Chapter 6 Momentum 1.MOMENTUM Momentum - inertia in motion Momentum = mass times velocity Units - kg m/s or sl ft/s](https://reader035.vdocuments.us/reader035/viewer/2022081511/56649d1a5503460f949ef4f7/html5/thumbnails/3.jpg)
1. MOMENTUM
• Momentum - inertia in motion• Momentum = mass times
velocityvmp
Units - kg m/s or sl ft/s
![Page 4: Chapter 6 Momentum 1.MOMENTUM Momentum - inertia in motion Momentum = mass times velocity Units - kg m/s or sl ft/s](https://reader035.vdocuments.us/reader035/viewer/2022081511/56649d1a5503460f949ef4f7/html5/thumbnails/4.jpg)
2. IMPULSE
• Collisions involve forces (there is a v).
• Impulse = force times time.
ΔtFI
Units - N s or lb s
![Page 5: Chapter 6 Momentum 1.MOMENTUM Momentum - inertia in motion Momentum = mass times velocity Units - kg m/s or sl ft/s](https://reader035.vdocuments.us/reader035/viewer/2022081511/56649d1a5503460f949ef4f7/html5/thumbnails/5.jpg)
3. IMPULSE CHANGES MOMENTUM
Impulse = change in momentum
amF
vmtF
tv
mF
![Page 6: Chapter 6 Momentum 1.MOMENTUM Momentum - inertia in motion Momentum = mass times velocity Units - kg m/s or sl ft/s](https://reader035.vdocuments.us/reader035/viewer/2022081511/56649d1a5503460f949ef4f7/html5/thumbnails/6.jpg)
vmtF
pI
)vmvm(tF if
)vv(mtF if
)pp(tF if
![Page 7: Chapter 6 Momentum 1.MOMENTUM Momentum - inertia in motion Momentum = mass times velocity Units - kg m/s or sl ft/s](https://reader035.vdocuments.us/reader035/viewer/2022081511/56649d1a5503460f949ef4f7/html5/thumbnails/7.jpg)
I
t
Case 1Increasing Momentum
Follow through
Examples:Long Cannons
Driving a golf ballCan you think of others?
t p
I
F
p
![Page 8: Chapter 6 Momentum 1.MOMENTUM Momentum - inertia in motion Momentum = mass times velocity Units - kg m/s or sl ft/s](https://reader035.vdocuments.us/reader035/viewer/2022081511/56649d1a5503460f949ef4f7/html5/thumbnails/8.jpg)
Video ClipVideo Clip
Tennis racquet and ballTennis racquet and ball
![Page 9: Chapter 6 Momentum 1.MOMENTUM Momentum - inertia in motion Momentum = mass times velocity Units - kg m/s or sl ft/s](https://reader035.vdocuments.us/reader035/viewer/2022081511/56649d1a5503460f949ef4f7/html5/thumbnails/9.jpg)
tF
Case 2Decreasing Momentum over a
Long Time
Examples:Rolling with the Punch
Bungee JumpingCan you think of others?
Ip
tF
Warning – May be dangerous
![Page 10: Chapter 6 Momentum 1.MOMENTUM Momentum - inertia in motion Momentum = mass times velocity Units - kg m/s or sl ft/s](https://reader035.vdocuments.us/reader035/viewer/2022081511/56649d1a5503460f949ef4f7/html5/thumbnails/10.jpg)
Case 3Decreasing Momentum over a
Short Time
Examples:Boxing (leaning into punch)
Head-on collisionsCan you think of others?
tFIp
![Page 11: Chapter 6 Momentum 1.MOMENTUM Momentum - inertia in motion Momentum = mass times velocity Units - kg m/s or sl ft/s](https://reader035.vdocuments.us/reader035/viewer/2022081511/56649d1a5503460f949ef4f7/html5/thumbnails/11.jpg)
4. BOUNCING
There is a greater impulse with bouncing.
Example:Pelton Wheel
Demo – Impulse PendulumDemo – Impulse Pendulum
![Page 12: Chapter 6 Momentum 1.MOMENTUM Momentum - inertia in motion Momentum = mass times velocity Units - kg m/s or sl ft/s](https://reader035.vdocuments.us/reader035/viewer/2022081511/56649d1a5503460f949ef4f7/html5/thumbnails/12.jpg)
• Consider a hard ball and a clay ball that have +10 units of momentum each just before hitting a wall.
• The clay ball sticks to the wall and the hard ball bounces off with -5 units of momentum.
• Which delivered the most “punch” to the wall?
![Page 13: Chapter 6 Momentum 1.MOMENTUM Momentum - inertia in motion Momentum = mass times velocity Units - kg m/s or sl ft/s](https://reader035.vdocuments.us/reader035/viewer/2022081511/56649d1a5503460f949ef4f7/html5/thumbnails/13.jpg)
Initial momentum of the clay ball is 10.Final momentum of clay ball is 0.The change is 0 - 10 = - 10.It received - 10 impulse so itapplied + 10 to the wall.
![Page 14: Chapter 6 Momentum 1.MOMENTUM Momentum - inertia in motion Momentum = mass times velocity Units - kg m/s or sl ft/s](https://reader035.vdocuments.us/reader035/viewer/2022081511/56649d1a5503460f949ef4f7/html5/thumbnails/14.jpg)
Initial momentum of the hard ball is 10.Final momentum of hard ball is - 5.The change is - 5 - 10 = - 15.It received - 15 impulse so itapplied + 15 to the wall.
![Page 15: Chapter 6 Momentum 1.MOMENTUM Momentum - inertia in motion Momentum = mass times velocity Units - kg m/s or sl ft/s](https://reader035.vdocuments.us/reader035/viewer/2022081511/56649d1a5503460f949ef4f7/html5/thumbnails/15.jpg)
5. CONSERVATION OF MOMENTUM
Example:Rifle and bullet
Demo - Rocket balloons (several)Demo - Clackers Video - Cannon recoilVideo - Rocket scooter
![Page 16: Chapter 6 Momentum 1.MOMENTUM Momentum - inertia in motion Momentum = mass times velocity Units - kg m/s or sl ft/s](https://reader035.vdocuments.us/reader035/viewer/2022081511/56649d1a5503460f949ef4f7/html5/thumbnails/16.jpg)
Consider two objects, 1 and 2, and assume that no external forces are acting on the system composed of these two particles.
i11f111 vmvmtF
Impulse applied to object 1
i22f222 vmvmtF
i22f22i11f11 vmvmvmvm0
Impulse applied to object 2
Total impulseappliedto system
f22f11i22i11 vmvmvmvm
or
Apply Newton’s Third Law21 FF
tFtFor 21
![Page 17: Chapter 6 Momentum 1.MOMENTUM Momentum - inertia in motion Momentum = mass times velocity Units - kg m/s or sl ft/s](https://reader035.vdocuments.us/reader035/viewer/2022081511/56649d1a5503460f949ef4f7/html5/thumbnails/17.jpg)
•Internal forces cannot cause a change in momentum of the system.
•For conservation of momentum, the external forces must be zero.
![Page 18: Chapter 6 Momentum 1.MOMENTUM Momentum - inertia in motion Momentum = mass times velocity Units - kg m/s or sl ft/s](https://reader035.vdocuments.us/reader035/viewer/2022081511/56649d1a5503460f949ef4f7/html5/thumbnails/18.jpg)
Chapter 6 Review Questions
![Page 19: Chapter 6 Momentum 1.MOMENTUM Momentum - inertia in motion Momentum = mass times velocity Units - kg m/s or sl ft/s](https://reader035.vdocuments.us/reader035/viewer/2022081511/56649d1a5503460f949ef4f7/html5/thumbnails/19.jpg)
The product of mass times velocity is most appropriately called
(a) impulse
(b) change in momentum
(c) momentum
(d) change in impulse
![Page 20: Chapter 6 Momentum 1.MOMENTUM Momentum - inertia in motion Momentum = mass times velocity Units - kg m/s or sl ft/s](https://reader035.vdocuments.us/reader035/viewer/2022081511/56649d1a5503460f949ef4f7/html5/thumbnails/20.jpg)
You jump off a table. When you land on the floor you bend your knees during the landing in order to
(a) make smaller the impulse applied to you by the floor
(b) make smaller the force applied to you by the floor
(c) both (a) and (b)
![Page 21: Chapter 6 Momentum 1.MOMENTUM Momentum - inertia in motion Momentum = mass times velocity Units - kg m/s or sl ft/s](https://reader035.vdocuments.us/reader035/viewer/2022081511/56649d1a5503460f949ef4f7/html5/thumbnails/21.jpg)
An egg dropped on carpet has a better chance of surviving than an egg dropped on concrete. The reason why is because on carpet the time of impact is longer than for concrete and thus the force applied to the egg will be smaller.(a) True(b) False
![Page 22: Chapter 6 Momentum 1.MOMENTUM Momentum - inertia in motion Momentum = mass times velocity Units - kg m/s or sl ft/s](https://reader035.vdocuments.us/reader035/viewer/2022081511/56649d1a5503460f949ef4f7/html5/thumbnails/22.jpg)
6. COLLISIONS
Collisions involve forces internal to colliding bodies.
Elastic collisions - conserve energy and momentum
Inelastic collisions - conserve momentum
Totally inelastic collisions - conserve momentum and objects stick together
![Page 23: Chapter 6 Momentum 1.MOMENTUM Momentum - inertia in motion Momentum = mass times velocity Units - kg m/s or sl ft/s](https://reader035.vdocuments.us/reader035/viewer/2022081511/56649d1a5503460f949ef4f7/html5/thumbnails/23.jpg)
Demos and Videos
Demo – Air track collisions (momentum & Demo – Air track collisions (momentum & energy)energy)Demo - Momentum balls (momentum & energy)Demo - Momentum balls (momentum & energy)Demo - Hovering disks (momentum & energy)Demo - Hovering disks (momentum & energy)Demo - Small ball/large ball dropDemo - Small ball/large ball dropDemo - Funny BallsDemo - Funny BallsVideo - Two Colliding Autos (momentum)Video - Two Colliding Autos (momentum)
Terms in parentheses represent what is conserved.Terms in parentheses represent what is conserved.
![Page 24: Chapter 6 Momentum 1.MOMENTUM Momentum - inertia in motion Momentum = mass times velocity Units - kg m/s or sl ft/s](https://reader035.vdocuments.us/reader035/viewer/2022081511/56649d1a5503460f949ef4f7/html5/thumbnails/24.jpg)
Collision between two objects of the same mass. One mass is at rest.
Collision between two objects. One not at rest initially has twice the mass.
Collision between two objects. One at rest initially has twice the mass.
Simple Examples of Head-On Collisions
(Energy and Momentum are Both Conserved)
![Page 25: Chapter 6 Momentum 1.MOMENTUM Momentum - inertia in motion Momentum = mass times velocity Units - kg m/s or sl ft/s](https://reader035.vdocuments.us/reader035/viewer/2022081511/56649d1a5503460f949ef4f7/html5/thumbnails/25.jpg)
Head-On Totally Inelastic Collision Example
• Let the mass of the truck be 20 times the mass of the car.
• Using conservation of momentum, we get
mph60vtruck mph60vcar
![Page 26: Chapter 6 Momentum 1.MOMENTUM Momentum - inertia in motion Momentum = mass times velocity Units - kg m/s or sl ft/s](https://reader035.vdocuments.us/reader035/viewer/2022081511/56649d1a5503460f949ef4f7/html5/thumbnails/26.jpg)
v)m21()mph60(m)mph60(m20
v21)mph60(19
)mph60(2119
v
mph3.54v
initial momentum of system = final momentum of system
![Page 27: Chapter 6 Momentum 1.MOMENTUM Momentum - inertia in motion Momentum = mass times velocity Units - kg m/s or sl ft/s](https://reader035.vdocuments.us/reader035/viewer/2022081511/56649d1a5503460f949ef4f7/html5/thumbnails/27.jpg)
• Remember that the car and the truck exert equal but oppositely directed forces upon each other.
• What about the drivers?• The truck driver undergoes the same
acceleration as the truck, that is
tmph7.5
tmph)603.54(
![Page 28: Chapter 6 Momentum 1.MOMENTUM Momentum - inertia in motion Momentum = mass times velocity Units - kg m/s or sl ft/s](https://reader035.vdocuments.us/reader035/viewer/2022081511/56649d1a5503460f949ef4f7/html5/thumbnails/28.jpg)
• The car driver undergoes the same acceleration as the car, that is
tmph3.114
t)mph60(mph3.54
The ratio of the magnitudes of these two accelerations is
207.53.114
![Page 29: Chapter 6 Momentum 1.MOMENTUM Momentum - inertia in motion Momentum = mass times velocity Units - kg m/s or sl ft/s](https://reader035.vdocuments.us/reader035/viewer/2022081511/56649d1a5503460f949ef4f7/html5/thumbnails/29.jpg)
Remember to use Newton’s Second Law to see the forces involved.
• For the truck driver his mass times his acceleration gives
F
am
For the car driver his mass times his greater acceleration gives
ma
F
![Page 30: Chapter 6 Momentum 1.MOMENTUM Momentum - inertia in motion Momentum = mass times velocity Units - kg m/s or sl ft/s](https://reader035.vdocuments.us/reader035/viewer/2022081511/56649d1a5503460f949ef4f7/html5/thumbnails/30.jpg)
•
• Your danger is of the order of twenty times greater than that of the truck driver.
TRUCKS , big trucks that is.• Don’t mess with T
![Page 31: Chapter 6 Momentum 1.MOMENTUM Momentum - inertia in motion Momentum = mass times velocity Units - kg m/s or sl ft/s](https://reader035.vdocuments.us/reader035/viewer/2022081511/56649d1a5503460f949ef4f7/html5/thumbnails/31.jpg)
7. More Complicated Collisions
Vector Addition of Momentum
![Page 32: Chapter 6 Momentum 1.MOMENTUM Momentum - inertia in motion Momentum = mass times velocity Units - kg m/s or sl ft/s](https://reader035.vdocuments.us/reader035/viewer/2022081511/56649d1a5503460f949ef4f7/html5/thumbnails/32.jpg)
Collision between two objects of the same mass. One mass is at rest.
Example of Non-Head-On Collisions
(Energy and Momentum are Both Conserved)
If you vector add the total momentum after collision,you get the total momentum before collision.
![Page 33: Chapter 6 Momentum 1.MOMENTUM Momentum - inertia in motion Momentum = mass times velocity Units - kg m/s or sl ft/s](https://reader035.vdocuments.us/reader035/viewer/2022081511/56649d1a5503460f949ef4f7/html5/thumbnails/33.jpg)
Examples:Colliding cars
Exploding bombs
Video - Collisions in 2-DVideo - Collisions in 2-D
![Page 34: Chapter 6 Momentum 1.MOMENTUM Momentum - inertia in motion Momentum = mass times velocity Units - kg m/s or sl ft/s](https://reader035.vdocuments.us/reader035/viewer/2022081511/56649d1a5503460f949ef4f7/html5/thumbnails/34.jpg)
Chapter 6 Review Questions
![Page 35: Chapter 6 Momentum 1.MOMENTUM Momentum - inertia in motion Momentum = mass times velocity Units - kg m/s or sl ft/s](https://reader035.vdocuments.us/reader035/viewer/2022081511/56649d1a5503460f949ef4f7/html5/thumbnails/35.jpg)
In which type of collision is energy conserved?
(a) elastic(b) inelastic(c) totally inelastic(d) All of the above(e) None of the above
![Page 36: Chapter 6 Momentum 1.MOMENTUM Momentum - inertia in motion Momentum = mass times velocity Units - kg m/s or sl ft/s](https://reader035.vdocuments.us/reader035/viewer/2022081511/56649d1a5503460f949ef4f7/html5/thumbnails/36.jpg)
A Mack truck and a Volkswagen have a collision head-on. Which driver experiences the greater force?
(a) Mack truck driver(b) Volkswagen driver(c) both experience the same force