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## High school physics - NGSS

### Course: High school physics - NGSS>Unit 1

Lesson 2: Introduction to momentum

# Introduction to momentum

Momentum is defined for a particular frame of reference; it is the mass times the velocity of the object. Created by Sal Khan.

## Want to join the conversation?

• If you drove the truck at 20 m/s into a stationary formula one car, assuming all the momentum was transferred from the truck into the car, would the car have a momentum of 600,000 kg*m/s just after the time of impact?

If so, could you calculate the velocity of the car?
• yes the standard unit of velocity magnitude (also known as speed ) is the meter per second (m/s). ... If you are driving the car, the velocity of the car relative to your body is zero. If you stand by the side of the road, the velocity of the car relative to you is 20 m/s northward.

hope this helped :/
• what is the difference between mass, inertia, and momentum?
• 1. Mass is the quantity of matter which an object contains.
2. Inertia is the tendency to move or stay at rest.
3. Momentum is kind of how much difficult to stop an object.

The relationship between these is if an object has more matter then it will have more inertia. So according to p=mv, it will have greater momentum.

Think about a train and a normal car. Apparently, the train has much more mass than the car. So, it will have more inertia. So when you push the breaks of these two vehicles at the same time, it will be more difficult to stop the train.
(1 vote)
• How was momentum as mass-times-velocity discovered as a significant quantity? Why not, say, mass-velocity ratio or some other quantity? How did physicists arrive at this specific product as a significant one to compute for moving objects?
(1 vote)
• How fast would it go if it were traveling faster distance/velocity based on the rate of speed at which it was traveling?
(1 vote)
• If we had a scenario where the car was only moving 19 m/s rather than 20 m/s like the 30,000 kg truck, would the momentum of the truck to our frame in the car be 30,000 kg m/s from (20-19 m/s) x 30,000 kg?
(1 vote)
• Why does he call it an 18 wheeler when it has 14 wheels, 7 on each side?
• The rear two axels of both the truck and the trailer have four wheels each. In total that's four axels with four wheels (4x4=16). And then adding the front axle of the truck which only has two wheels gives us the 18 wheels.
• KE=1/2mv^2, p=mv, therefore p=2KE/v, so as v increases p decreases. does this make sense? Thank You!
• We have p = 2KE/v, but that doesn't necessarily mean that as v increases p decreases. Note that KE is dependent on v^2, so the factor of increase in KE outweights that of v itself.
(1 vote)
• Just wondering...
How would you convert it into miles rather than km?