Impulse and MomentumCollisions and conservation of momentum
Chapter 9Pages 229-255
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I Can: Given the mass, velocity and time it takes to stop an object in an inelastic collision, determine the momentum and impulse of the collision.
9.1 Impulse and Momentum
Scan page 230Write down the following information:Define Impulse, Momentum, and Impulse-Momentum theoremWrite out the formulas for momentum and the impulse-momentum theoremWhat are the units for momentum? Impulse?
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I Can: Given the mass, velocity and time it takes to stop an object in an inelastic collision, determine the momentum and impulse of the collision.
Impulse and Momentum in a crash
Read the last 2 paragraphs on page 231.What can result in a large impulse?What happens to the driver when a crash suddenly stops a car?How does an airbag reduce the likelihood of injuries?
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I Can: Given the mass, velocity and time it takes to stop an object in an inelastic collision, determine the momentum and impulse of the collision.
p.233 Practice problems
m= 725 kg, v = 115 km/h (change to m/s)23200kgm/s eastwardUse the above momentum to find v when m = 2175 kgt= 2.0 s, F = 5000 N10000 Ns westwardpf= 13200kgm/s east, v = ?Skipm = ____ kg, vi= ___ m/s,vf= ____ m/s, t = ____ sSkip∆p = 5280kgm/s (also equal to change in impulse)F = 88.0 NOn your own
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I Can: Given the mass, velocity and time it takes to stop an object in an inelastic collision, determine the momentum and impulse of the collision.
Angular Momentum
Write the formulas on p.233 and 234Read 234-235 about the forces acting, planets orbiting the Sun, divers off a diving board, and ice-skaters.Be prepared for either a short-answer or essay question on your next test.
5
I Can: Given the mass, velocity and time it takes to stop an object in an inelastic collision, determine the momentum and impulse of the collision.
Individual assignment
9.1 section reviewP.235 (#6-12)Due by the end of class today
6
I Can: Given the mass, velocity and time it takes to stop an object in an inelastic collision, determine the momentum and impulse of the collision.
Bellringer
I Can: Given the mass, velocity and time it takes to stop an object in an inelastic collision, determine the momentum and impulse of the collision.
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Which has greater momentum, a 2.0kg hockey puck moving east at 2.5m/s or a 1.3kg hockey puck moving south at 3.0m/s?A 147.25 kilogram motorcycle is moving at a speed of 69.75 m/s. What is the momentum of the cycle?If the motorcycle above crashes into a wall and stops in a time of 0.05 seconds, how much force acted on the cycle to bring it to a stop?
9.2 Conservation of momentum
Read on p.236 about Momentum in a Closed, Isolated System.Define all bold terms.Why does it matter if the system is closed and isolated?
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I Can: Given the mass, velocity and time it takes to stop an object in an inelastic collision, determine the momentum and impulse of the collision.
Collisions
When objects collide in a closed, isolated system, momentum is conserved.Equation:pCi+pDi=pCf+pDfExample Problem 2 on p.237togetherSketch the situation for all problems and label all variables (different m and v)Pay attention to whether objects stick together or not – this will change the equation slightly.
9
I Can: Given the mass, velocity and time it takes to stop an object in an inelastic collision, determine the momentum and impulse of the collision.
Practice problems
P.238 (#13-18)13. 1.1 m/s14. 0.034 m/s15. 1237 m/s16. 2.8 m/s17. 6.7 m/s18. 2.0 m/s in the opposite direction
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I Can: Given the mass, velocity and time it takes to stop an object in an inelastic collision, determine the momentum and impulse of the collision.
Recoil
Read on p.239 about propulsion in space.Go over Example Problem 3 together (p.240)What is the equation for a recoil problem?Practice problems on p.24019. 7.91 m/s20. 9.0 cm/s to the right21. 2.8 m/s in the opposite direction
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I Can: Given the mass, velocity and time it takes to stop an object in an inelastic collision, determine the momentum and impulse of the collision.
Two-dimensional collisions
Time to add vectors and angles!Split all problems into the x and y directionsRight triangles!!Go over Example Problem 4 together (p.242)Practice p.243 (#22-25)22. 11.2 m/s, 36.6onorth of west23. 18.1 m/s, 15.9osouth of east24. 3.5 m/s, 30.0oto the right2.0 m/s, 60.0oto the left25. 22.1 m/s, yes
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I Can: Given the mass, velocity and time it takes to stop an object in an inelastic collision, determine the momentum and impulse of the collision.
Conservation of angular momentum
Read p.243-245 about conservation of angular momentum.Pay special attention to explanation of Earth’s rotation, an ice-skater’s rotation, tops, and gyroscopes.
13
I Can: Given the mass, velocity and time it takes to stop an object in an inelastic collision, determine the momentum and impulse of the collision.
9.2 section review
P.245 (#28-31) – due todayChapter 9 review p.250-253(#32-42, 48-64even, 73-82)
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I Can: Given the mass, velocity and time it takes to stop an object in an inelastic collision, determine the momentum and impulse of the collision.
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