# Tag Info

## New answers tagged velocity

6

Your assertion that only relative speeds matter is absolutely correct. However, you might want to look at the velocity addition of special relativity for space ships or whatever else travelling at relativistic speeds. For speeds high above our everyday experience, two things which, relative to us, travel in opposite directions with a speed $v$ will not see ...

0

It would be safer to swing closer to the hill if I am understanding your question. I've never seen the movie you are talking about but, in general, a lesser height would provide a smaller time frame in which the jumpers would accelerate. A lower impact velocity would result in a higher chance of withstanding the crash.

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The expression "change in direction" implies some sort of discontinuity in motion, where in the referenced graphs, there is none. One could easily choose a different frame of reference such that the oscillating object appears never to change direction, only periodically speed up and slow down. The fact that the velocity value at the point in question happens ...

1

Is it because acceleration is only the difference in velocity at two different points in time and not one? I think you've basically hit on the answer to your question here. Acceleration is the derivative of velocity with respect to time, which means it is the instantaneous rate that the velocity is changing with time. Acceleration is a measure of how ...

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Starting from the conservation of mass: $$\dot m_{1}=\dot m_{2}$$ This translates to $$\rho_{1} S_{1} V_{1}=\rho_{2} S_{2} V_{2}$$ Assuming incompressible flow, thus $\rho_{1}=\rho_{2}$ gives: $$S_{1} V_{1}= S_{2} V_{2}$$ With $S_{1} V_{1} = Q_{1}$ , the formula you are using. This formula follows directly from the mass balance, with only the ...

1

When you are pressing against the wall, what you are feeling is the reaction of the wall to the force you are exerting with your muscles; since this force is spread over the area of your hand, the pressure is not very large: no pain. In contrast, when you hit the wall (say with a closed fist), the force that is exerted is the force needed to stop the ...

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It's the same reason why simply holding the mass over your head uses energy, even though the mass is not moving. And the reason is the way your muscle tissue works, which is to continually contract and then relax - obviously with different parts of the same muscle firing off at different times.

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HINT: From conservation of energy, you can find the velocity at the release point; after that it will follow a projectile motion. You can thus write equation of trajectory from the projectile motion.

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