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# Relative velocity watch

1. i think the title is right, but here goes.

What i mean is if a car travelling at 60ms^-1 crashes into a wall, the impact force is 60ms^1.

But i was thinking what the impact force was if the car was a liquid- water travelling at 60ms^-1. Would the impact force still be 60ms^-1??
2. (Original post by saiyamana)
i think the title is right, but here goes.

What i mean is if a car travelling at 60ms^-1 crashes into a wall, the impact force is 60ms^1.

But i was thinking what the impact force was if the car was a liquid- water travelling at 60ms^-1. Would the impact force still be 60ms^-1??
I don't see how the impact force can be measured in ms^-1 - those are velocity units. Forces are measured in Newtons (or equivalently kg m s^-2).

The impact force would depend on the momentum of the object and over how long the force was applied, using the

Impulse = force x time

rule. That it was a car or water that had that momentum shouldn't matter.
3. (Original post by saiyamana)
i think the title is right, but here goes.

What i mean is if a car travelling at 60ms^-1 crashes into a wall, the impact force is 60ms^1.

But i was thinking what the impact force was if the car was a liquid- water travelling at 60ms^-1. Would the impact force still be 60ms^-1??
Don't understand, why the impact force has unit ms^-1?
4. lol, never mind, i'm gettin confused with my units.
5. well... does not matter what object it is... its the mass of the object that matters.... if one tonnes worth of foam collides with you... you can still feel the force of that one tonne.... although.. if you are doing material coursework... then the material matters as some provide 'cushioning'... but the uncushioned force is identical

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