Answer:
A molecule is something every mass has and is very small
Explanation:
Meters per second squared:

If you think about it, acceleration is about how fast speed changes. Speed is measured in meters per second:

So if you take that and just measure it over time, you get meters per second squared.
I think it is because the electrons repel each other
Answer:
The magnitude of change in momentum is (2mv).
Explanation:
The momentum of an object is given by the product of mass and velocity with which it is moving.
Let the mass of ball is m. A tennis player smashes a ball of mass m horizontally at a vertical wall. The ball rebounds at the same speed v with which it struck the wall.
Initial speed of the ball is v and final speed, when it rebounds, is (-v). The change in momentum is given by :
p = final momentum - initial momentum

So, the magnitude of change in momentum is (2mv).
Stop and look to see if anything is coming