# What is momentum?

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#1
Hi, I'm a GCSE student and I've had it explained to me that momentum is equal to mass times velocity. But what is it really? And why do we need to know it? Also, if it's something to do with mass and velocity, why not just add the two together instead of times them? Thanks, any answers would be appreciated.
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4 weeks ago
#2
Momentum is something which is always conserved (well at GCSE it is). It’s just a quantity which you have to know how to calculate, nothing fancy (unless you take a level physics, where there will be changes in momentum) For example, if A (mass a) collided into B (mass b) at a velocity of X and B is stationary, then the momentum before the collision = aX b x 0. After the collision, the two masses join and travel at velocity Y; the momentum will be the same as before. but since the two masses are moving together, it will be aY bY. So overall aX = aY bY. I hope that makes sense!
Last edited by XHannahR; 4 weeks ago
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4 weeks ago
#3
(Original post by IlianaF)
Hi, I'm a GCSE student and I've had it explained to me that momentum is equal to mass times velocity. But what is it really? And why do we need to know it? Also, if it's something to do with mass and velocity, why not just add the two together instead of times them? Thanks, any answers would be appreciated.
The momentum - in mechanical sense - is a movement state with a direction and a magnitude. The magnitude itself is a momentum transfer: in the moment an object in movement state hits another one (in rest position) or a hindrance, a force is transferred. The more mass and velocity the moved object has, the greater the momentum transfer. This for instance is considered in safety laboratories to investigate the damages cars cause when they hit a hindrance as a wall in order to optimize the safety in cars.
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