Momentum | GCSE Physics | Doodle Science

Показать описание

Doodle Science teaches you high school physics in a less boring way in almost no time!

Script:
Every moving object has momentum. This is the tendency of the object to keep moving in the same direction unless acted upon by an external force. You'll have a hard time trying to change the direction of movement of an object with a lot of momentum. Unless you're Neo of course.

It depends on an object's mass and velocity. So the equation for calculating it is p=mv where p is the momentum in kg m/s; m is the mass in kg and v is the velocity in m/s. A basic example of this would be the momentum of a 20kg trolley travelling at 2m/s would have a momentum of 40kg m/s.

However, calculating momentum in a collision isn't as straight forward. To do this we use the conservation of momentum law, which states the amount of momentum before the collision is equal to the momentum after the collision. If a car has a mass of 1000kg and is travelling at 7m/s and hits the back of another car with a mass of 1500kg which was stationary before the collision, then we can work out the velocity of the two cars as they roll off as a single mass. Firstly we work out the momentum of each object individually. So the first car has a momentum of 10500kg m/s and the second car has a momentum of 0kg m/s. Then we add them together, but because velocity has direction, so does momentum and so we have to make one of the values negative to show it's moving in the opposite direction. In this case it doesn't matter because it's zero. Now we know the momentum before the collision we also know it after the collision so all we do now is add the masses of the two cars together and divide it from the momentum to get 4.2m/s.

Рекомендации по теме

Комментарии

Isn’t 7 x 1000 = 7000 and not 10500? Or am I missing something

bonitamuriuki

They put this video in my Seneca homework and I literally cried because I didn’t understand where the number 10500 came from - I’m a bit of a nerd and I understand things relatively easily so it was really frustrating that I wasn’t understanding 😂😤 I’m so glad that it was a mistake

abigailtaylor

Isn't the momentum of the first object and thus of both objects combined 7000 kg m/s, which results in a post-crash velocity of 2.8 m/s ?

dominikdrechsler