Acceleration
In Physics, acceleration occurs when an object is speeding up or slowing down, that is: the rate at which an object changes its velocity. This term "accelerate" is usually used to refer to something that is moving fast, but actually this is not the right meaning for this, because if an object is moving fast but not changing its velocity, then is not accelerating.
Acceleration can be expressed by the formula :
a = Vf - Vi / t where Vf stands for Final Velocity and Vi for Initial Velocity divided by the time.
In certain situations, acceleration can also be constant if as each second, the velocity change the same amount. The units for acceleration are meters per second square (m/s/s).
relating to football
During a football game, the players keep running through the field and following the player who is holding the ball. But sometimes they have to stop. When the player is at rest and then starts to run or is running and then stops, we can say that this player is accelerating: he is changing his velocity in a certain amount of time.
Review Questions
A football player is at rest and then starts to run at 10 m/s during 20 seconds. What is the players acceleration?
0.5 m/s/s
If one car is moving at 20 m/s and another one at 30 m/s, which one is experiencing more acceleration? (considering that both were at rest)
30 m/s