Momentum, Impulse and Recoil. A truck is rolling down a hill than a roller skater with the same...
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Transcript of Momentum, Impulse and Recoil. A truck is rolling down a hill than a roller skater with the same...
![Page 1: Momentum, Impulse and Recoil. A truck is rolling down a hill than a roller skater with the same speed; which has the greater momentum? Momentum.](https://reader036.fdocuments.us/reader036/viewer/2022062500/5697bffb1a28abf838cc0fc6/html5/thumbnails/1.jpg)
Momentum, Impulse and Recoil
![Page 2: Momentum, Impulse and Recoil. A truck is rolling down a hill than a roller skater with the same speed; which has the greater momentum? Momentum.](https://reader036.fdocuments.us/reader036/viewer/2022062500/5697bffb1a28abf838cc0fc6/html5/thumbnails/2.jpg)
• A truck is rolling down a hill than a roller skater with the same speed; which has the greater momentum?
Momentum
![Page 3: Momentum, Impulse and Recoil. A truck is rolling down a hill than a roller skater with the same speed; which has the greater momentum? Momentum.](https://reader036.fdocuments.us/reader036/viewer/2022062500/5697bffb1a28abf838cc0fc6/html5/thumbnails/3.jpg)
Momentum
• Momentum is inertia in motion!
• Momentum = mass x velocity
• Momentum (p) = mv
• p= mass x speed (when direction is not important)
• A greater mass but the same speed will lead to a greater momentum
![Page 4: Momentum, Impulse and Recoil. A truck is rolling down a hill than a roller skater with the same speed; which has the greater momentum? Momentum.](https://reader036.fdocuments.us/reader036/viewer/2022062500/5697bffb1a28abf838cc0fc6/html5/thumbnails/4.jpg)
Decreasing Momentum
• Why does a car driven into a haystack at the same speed suffer less damage than one driven into a brick wall?
![Page 5: Momentum, Impulse and Recoil. A truck is rolling down a hill than a roller skater with the same speed; which has the greater momentum? Momentum.](https://reader036.fdocuments.us/reader036/viewer/2022062500/5697bffb1a28abf838cc0fc6/html5/thumbnails/5.jpg)
Impulse
• Impulse = F∆ t
• This is the force x time interval
• Impulse = change in momentum
• F ∆ t = ∆ (mv) [change in impulse = change in momentum
• If t increases and ∆ (mv) is constant then F decreases.
• This is the principle of an air bag in a car.
![Page 6: Momentum, Impulse and Recoil. A truck is rolling down a hill than a roller skater with the same speed; which has the greater momentum? Momentum.](https://reader036.fdocuments.us/reader036/viewer/2022062500/5697bffb1a28abf838cc0fc6/html5/thumbnails/6.jpg)
• Why does the boxer who moves back with a punch feel less pain than the boxer who moves into the punch?
![Page 7: Momentum, Impulse and Recoil. A truck is rolling down a hill than a roller skater with the same speed; which has the greater momentum? Momentum.](https://reader036.fdocuments.us/reader036/viewer/2022062500/5697bffb1a28abf838cc0fc6/html5/thumbnails/7.jpg)
Changes in Momentum
• The boxer increases the time taken for the impact and therefore reduces the force of the impact.
• Ft = change in momentum
![Page 8: Momentum, Impulse and Recoil. A truck is rolling down a hill than a roller skater with the same speed; which has the greater momentum? Momentum.](https://reader036.fdocuments.us/reader036/viewer/2022062500/5697bffb1a28abf838cc0fc6/html5/thumbnails/8.jpg)
• How does this runaway truck ramp use the laws of physics?
![Page 9: Momentum, Impulse and Recoil. A truck is rolling down a hill than a roller skater with the same speed; which has the greater momentum? Momentum.](https://reader036.fdocuments.us/reader036/viewer/2022062500/5697bffb1a28abf838cc0fc6/html5/thumbnails/9.jpg)
Bungee Jumping
• How does momentum and impulse relate to your changes of surviving a bungee jump?
![Page 10: Momentum, Impulse and Recoil. A truck is rolling down a hill than a roller skater with the same speed; which has the greater momentum? Momentum.](https://reader036.fdocuments.us/reader036/viewer/2022062500/5697bffb1a28abf838cc0fc6/html5/thumbnails/10.jpg)
• Ft = Impulse • Ft = ∆(mv)• The momentum, mv, is the amount gained
before the cord begins to stretch. Ft is the impulse the cord supplies to reduce the momentum to zero.
• Because the rubber cord stretches for a long time, a large time interval t ensures that a small average force F acts on the jumper.
• The cord typically stretches to about twice the original length during the fall.
![Page 11: Momentum, Impulse and Recoil. A truck is rolling down a hill than a roller skater with the same speed; which has the greater momentum? Momentum.](https://reader036.fdocuments.us/reader036/viewer/2022062500/5697bffb1a28abf838cc0fc6/html5/thumbnails/11.jpg)
Starter Questions
• How is the recoil of a rifle or cannon related to momentum conservation?
• A man is stranded in the middle of an ice rink that is perfectly frictionless. How can he get to the edge?
![Page 12: Momentum, Impulse and Recoil. A truck is rolling down a hill than a roller skater with the same speed; which has the greater momentum? Momentum.](https://reader036.fdocuments.us/reader036/viewer/2022062500/5697bffb1a28abf838cc0fc6/html5/thumbnails/12.jpg)
Conservation of Momentum• When the cannon is fired the
force on the cannonball inside the cannon barrel is equal and opposite to the force causing the cannon to recoil.
• Before the firing of the system is at rest and the momentum is zero.
• After the firing the net momentum, or total momentum, is still zero. Net momentum is neither gained nor lost.
![Page 13: Momentum, Impulse and Recoil. A truck is rolling down a hill than a roller skater with the same speed; which has the greater momentum? Momentum.](https://reader036.fdocuments.us/reader036/viewer/2022062500/5697bffb1a28abf838cc0fc6/html5/thumbnails/13.jpg)
Law of Conservation of Momentum
• In the absence of an external force, the momentum of a system remains unchanged.
• If a system undergoes changes wherein all the forces are internal, e.g. in atomic nuclei undergoing radioactive decay, cars colliding, or stars exploding, the net momentum remains constant.
![Page 14: Momentum, Impulse and Recoil. A truck is rolling down a hill than a roller skater with the same speed; which has the greater momentum? Momentum.](https://reader036.fdocuments.us/reader036/viewer/2022062500/5697bffb1a28abf838cc0fc6/html5/thumbnails/14.jpg)
• A bullet of mass 50g is fired from a gun of mass 2.0kg at a speed of 450 m/s. Calculate the speed of the recoil of the gun.
“In any interaction between two (or more objects) the total momentum of the objects remains constant”
Pi = PF
Recoil
![Page 15: Momentum, Impulse and Recoil. A truck is rolling down a hill than a roller skater with the same speed; which has the greater momentum? Momentum.](https://reader036.fdocuments.us/reader036/viewer/2022062500/5697bffb1a28abf838cc0fc6/html5/thumbnails/15.jpg)
Recoil of Gun
• Total momentum before and after is zero (as there is no velocity to start with).
• Momentum of bullet = Momentum of gun
![Page 16: Momentum, Impulse and Recoil. A truck is rolling down a hill than a roller skater with the same speed; which has the greater momentum? Momentum.](https://reader036.fdocuments.us/reader036/viewer/2022062500/5697bffb1a28abf838cc0fc6/html5/thumbnails/16.jpg)
Recoil Question
• A bullet of mass 0.01kg moves horizontally with a speed of 400m/s and embeds itself in a block of mass 0.39kg that is initially at rest on a frictionless table. Find the final velocity of the bullet and the block.
![Page 17: Momentum, Impulse and Recoil. A truck is rolling down a hill than a roller skater with the same speed; which has the greater momentum? Momentum.](https://reader036.fdocuments.us/reader036/viewer/2022062500/5697bffb1a28abf838cc0fc6/html5/thumbnails/17.jpg)
• Runaway truck ramp: http://www.northlight-images.co.uk/content_images/photography_tour/mon_5.jpg
• Truck: http://geoimages.berkeley.edu/geoimages/BainCalif/CAL400/runaway.jpg
• Roller Skater: http://www.mchenrycountyblog.com/uploaded_images/Roller-skates-715946.jpg
• Haystack: http://floridalawfirm.com/haystack.gif
• Brick wall: http://www.dailyhaha.com/_pics/car_crash_brick_wall.jpg
• Boxer avoids punch: http://cache.daylife.com/imageserve/01iL0EYd2c7Hd/610x.jpg
• Boxer lands punch: http://www.chinadaily.com.cn/sports/images/attachement/jpg/site1/20071205/001aa018ff9c08c0a6df0c.jpg
• Bungee Jumpers: http://uk.geocities.com/osfuk/osf/bungee.html
• Cannon firing: http://www.ottoleffler.com/psd/portfolio/Canon/ist2_2437935_fire_away.jpg
• Gun Recoil Pic: http://farm1.static.flickr.com/67/157553435_39e61a5113.jpg?v=0