Turn on thread page Beta
 You are Here: Home >< Physics

Momentum equation p=2mv someone explain pls watch

1. So p=mv normally but why does p=2mv when a molecule or something hits a wall and comes back?
2. V is velocity and when using velocity direction matters so if a ball hits a wall with speed V and rebounds with same speed, the speed of rebound will be -V. Hence, the momentum changed from V to 0 and then from 0 to -V.
3. (Original post by Radioactivedecay)
V is velocity and when using velocity direction matters so if a ball hits a wall with speed V and rebounds with same speed, the speed of rebound will be -V. Hence, the momentum changed from V to 0 and then from 0 to -V.
I get that it will become -V because opposite direction but what do you mean by "the momentum changed from V to 0 and then from 0 to -V". How does that make the equation p=2mv?
4. (Original post by aceplayyt)
I get that it will become -V because opposite direction but what do you mean by "the momentum changed from V to 0 and then from 0 to -V". How does that make the equation p=2mv?
Sorry I meant to say that the speed, not the momentum, changes from V to -V. First, lets clear one thing, 2mv is not the momentum of the object, it's the change of momentum that occurred ie, the impulse given. Recalling the impulse equation: I=mv-mu, but since we defined a direction we get m (-V)-mu=-2mV, so the total change in momentum is 2mV
5. Momentum is a vector so has both magnitude and direction. This direction is indicated using a minus sign (-mv) just means mv in the opposite direction. The change is momentum is the final momentum minus the initial momentum

Turn on thread page Beta

Related university courses

TSR Support Team

We have a brilliant team of more than 60 Support Team members looking after discussions on The Student Room, helping to make it a fun, safe and useful place to hang out.

This forum is supported by:
Updated: March 9, 2018
Today on TSR

Edexcel C4 Maths Unofficial Markscheme

Find out how you've done here

1,097

students online now

Exam discussions

Find your exam discussion here

Poll

The Student Room, Get Revising and Marked by Teachers are trading names of The Student Room Group Ltd.

Register Number: 04666380 (England and Wales), VAT No. 806 8067 22 Registered Office: International House, Queens Road, Brighton, BN1 3XE