8th Grade Science Motion II

8/10/2019 8th Grade Science Motion II

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MomentumAPPLICATION OF INERTIA


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QUIZ

1. What is the force required to move a 200 kg object at a rate of0.25 m/s 2?

2. The unit of Force is the Newton, which is equal to multiplying 1by 1 m/s 2. If I have units of 3000 grams or a rate of 3,600 m/mWhat do I need to do in each case to be able to get the correct

units and be able to obtain the value of Force in Newtons?3. What is the mass of an object that requires 95 N to move at a rat

of 5m/s 2?


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Momentum

Momentum is a characteristic of movingobjects that relates to mass and thevelocity of a moving object

Momentum can be calculated bymultiplying the objects mass by its

velocityMomentum = Mass x Velocity;

The momentum of an object is in thesame direction as the objects velocity


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Momentum

Momentum is transferred and the sum of the momentumof the objects is always conserved


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Conservation of Momentum

In the absence of an outside forcelike friction, the total momentumof objects that interact does notchange

Or stated another way:

the total momentum of anygroup of objects remains thesame, or is conserved, unlessoutside forces act on the objects


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Conservation of Momentum

100 kg 100 kg

3 m/s 2 m/s

Total Momentum = 100 kg x 3 m/s + 100 kg x 2 m/s

Total Momentum = 500 kg m/s

Two objects are moving and collide:Before collision After Collision

100 kg 100 kg

1 m/s 4 m/s

Total Momentum = 100 kg x 1 m/s + 100 kg x 4

Total Momentum = 500 kg m/s


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ProblemsOBJECTIVE: To Solve worded problems on momentum, air resistance, and free fall

What is the momentum of a car that travels northward with a velocity of 4 m/s and has a massof 900 kg?


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Problems

A car with mass of 900 kg travels northward with a velocity of 4 mA similar vehicle weighing 850 kg traveling in the same directioncollides with the first car. If the second vehicle is traveling at 2 m/s.What is the momentum of the second car? What is the totalmomentum of the system?


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Problems

A car with mass of 900 kg travels northward with a velocity of 4 m/A similar vehicle weighing 850 kg traveling in the same directioncollides with the first car. If the second vehicle is traveling at 2 m/s. the collision forces the second car to accelerate to 5 m/s, what is thevelocity of the first car after the collision?


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Problems

A car with mass of 750 kg travels northward with a velocity of 12 mA similar vehicle weighing 950 kg traveling in the same directioncollides with the first car. If the second vehicle is traveling at 6 m/s. the collision forces the second car to change its speed to 8 m/s, whatis the velocity of the first car after the collision?


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Problems

A car with mass of 900 kg travels northward with a velocity of 4 mA similar vehicle weighing 850 kg traveling in the same directioncollides with the first car. If the second vehicle is traveling at 2 m/s.the collision forces the second car to accelerate to 5 m/s in 5seconds, how much force needs to be applied to stop this vehicle?


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ProblemsA car with mass of 1000 kg travels northward with a velocity of 85 km/h. A similar vehicleweighing 2220 lbs traveling in the same direction collides with the first car. If the second vehiclis traveling at 40 km/h and the collision forces the second car to accelerate to 65 km/h, what isthe velocity of the first car after the collision?

8th Grade Science Motion II

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