Is inertia really independent of velocity?

Question

Definitely confused.

When we drive within speed limit, it is less likely to have traffic accidents. Is that related to inertia? Does it mean that inertia is somehow related to velocity?

Answer 1

When we drive slower, we have less momentum. This is clearly related to velocity.



And since momentum is conserved in collisions, you can see how this might affect the damage of a car crash.



Further, force is change in momentu/change in time. So if collisions occur in the same time frame, then the one with higher momentum changes will cause more damage (force).



In this sense, it isn't necessarily the velocity that is dangerous but the combination of mass and speed. Heavy slow things (tanks) are very dangerous.

Answer 2

The speed limit vs accident thing is probably related to order. If everyone is more organized, and doesnt have to anticipate as many variables when driving I would think there would be fewer accident. ie. every never sped, no one ever drank, every had there car maintanaced on schedule etc.





Interia is a resitance to a change in position.

i would have thought interia was depedent on velocity..but when i thought about it i think it is independent although it seems counterintuitive. EX: A parked car in neutral can be pushed to a new position with relatively little effort. On the other hand a car going at 100 mph that suddenly goes into netural is something you wouldnt want to try and push. The solution lies in the fact that in order to move the car you had to apply a certain force for a period of time. Lets say the velocity you gave it were 1 mph. For the car moving at 100 mph if you gave it same force for the same time it would indeed decrease in speed to 99mph before it hit you.

Answer 3

Mass and inertia are interchangeable terms.

Mass is dependent on velocity but only for relativistic velocities, that is, approaching the speed of light.

With regards to traffic accidents, I think velocity has more to do with problems than inertia. Traveling at higher speeds reduces the amount of time available to make corrections and avoid potential problems. But that can happen with high speeds for small cars and large trucks equally, so mass is not really an issue.