Post on 08-Jun-2018
transcript
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IMPULSE & CHANGE in MOMENTUM
1) What is impulse? If the rockets engines shown drive it upwards withan average force of 12 Newtons for a time of .75 seconds, Howmuch impulse will the rocket receive from the engines ?
(Note the units on Impulse)
- If a different engine were used that was rated at an impulseof 18 Newton Seconds, How long would this new engine haveto burn to provide the same average Force?
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2) A 65 kg passenger is in a car traveling at 20 mIs, The passengercrashes into a brick wall. If no seat belt or air bag is used theCollision takes .02 seconds to bring the persons body to a stop.(mostlyfrom harddashboard,or steeringwheel),If seat belt is usedcoUisiontime is extended to 0.1seconds,If airbag is usedcollisiontime is extended to 0.75 seconds. Explainwhat the result will bein terms of the averageforce pushingbackwardsonthe personsbody.
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How does Impulse tie intoChange in Momentum
3) Note Impulse is J=Ft. The momentumequation is P=mv.So the Change inmomentumequation wouldbe AP=rr\4v
(Note this could be Qdecrease or increase in momentum)
So now set up Newton's 2ndLaw Formula (F=ma)to show(Impulse) is always = (Changein Momentum)
4) So nownote -The impulseequation could be any of these -
J= -- -- --
The Changein momentumformula could be any of these -
bP= -- -- --
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5) In a collisionprocess a 50 kg driver of a car is slowed from25 m/s To rest in a period of ina period of 0.6 seconds.
- What is the drivers change inMomentum?
-What impulsemust act on the driver? What is the average forceacting over the time period of the collision?
L) A Golf club is swungat &strikes a 0.05 kg Golf ball. The Avg.Force on the ball is 20 N, for a time period of 0.1 sec.
. What impulseacts on the ball.
- What willthe balls change inmomentumbe ? What velocitywillit get?
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1) A 1200kg car traveling at 21 meter/see runs dead on into a .0005kg BUGona hot summer night. The bug was pretty much standing still, minding its
ownbusinessbefore the collision. > 2J r'I:;
(~- Use the law of conservation of momentum
To find velocity of pair after collision.
- Find the change in momentum and impulseon bug.
- Find the force on the bug iri the collision.
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, A 1.2kg baseball bat swings at and hits a .0001kg feather. The collisiontakes.009 seconds, and they become like a pairafter it. FIND-
~Velocity of pair after, Change inmomentum. of feather, Force onFeather.
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A soccer player accelerates a O.50..kilogramsoccer ball by kicking it with a net force of5.0 newtons.
The collision of the foot with theBall lasts for .3 seconds
a) - Find the impulse on the ball
';,) -Find the balls change in momentum, and change in velocity
iJWhat is the magnitude of the force of the soccerball on the player's foot? [1]
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@During a 5.0-second interval, an object's velocitychanges from 25 meters per second east to
15.meters per second east.
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(J) - Find the impulse on the lab cart, and change in momentum.
b} -Find the size and direction of the force on the cart
@ A..qo.-kilogr~,.~ threw a O.~idlograrr:t 'I
hallwitha.'-::-eo'ijriftlIleters: . rseOOnd. What.w~ tii~~~tu~"~fIi& irri~e that thestu-dent exerted 01:\the ball?
(1). 8.0 N.s(2) 78 N-s
(3) 4.0 x 102N.s .
(4) 1.0 x 1(]3N.s
Find the force on the student.
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If the student were on a skateboard and free to roll, what would his kickbackvelocity be ?
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A o.45-kilogramfootball traveJing at a speed of22 meters per second is caught by an84-kilogramstationary receiver. IT the footballcomes to rest in the receiver's arms, themagnitude of the impulse imparted to the-receiver by the ball is(1) 1800N.s (3) 4.4 N.s(2) 9.9 N.s (4) 3.8 N.s
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Find the force the receiver or the ball feel from the catch. (I~ c <.",rc.!-' hke5
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With what velocity would the receiver be knocked backward with fromthe catch?