Forgive me for being dense! I'm still not getting this at all
Quote from Tim:-
"Yes, this is true, but what you are looking for is force. In both these cases, the acceleration, a is huge, and the bike has a lower mass so therefore exerts much less force on the car in front"
So a car with more mass will exert more force on the car in front and move the car forward? If that's the case then why would a heavier bat not exert more force on a ball it strikes? Is it because you would not be able to swing the heavier bat as powerfully as a lighter one therefore negating the difference in mass?
Sorry, I'm really trying not to be difficult here, I did chemistry and biology at school not physics......and it was a long time ago!
Right....
In this system we have two masses, the ball and the bat. When hitting the ball we are imparting velocity to it. Velocity is directional. We are therefore changing the velocity of the ball. Let's take hitting a straight six as an example.
Going back to first principles, Newton's first law states that a body remains at rest or a constant velocity until a force is applied to it.
Then, applying Newton's second law, a body of mass m subject to a net force F undergoes an acceleration a that has the same direction as the force and a magnitude that is directly proportional to the force and inversely proportional to the mass, ie, F=ma.
acceleration = (velocity at end - velocity at start)/time
The bat held at the top of the backlift is in a state of rest, and will not move without applying the second law. To move the bat, we have to apply a force.
The force will cause acceleration of the bat to a velocity at which it will hit the ball.
When we strike the ball, lets assume we are trying to hit it as hard as we possibly can, which means, for a given bat mass, m, we need a maximum acceleration, a
max. To achieve a
max we have to apply as much force as we can, f
max.
As a person, you are restricted to f
max being governed by your strength. Acceleration is inversely proportional to mass.
If you therefore use a lighter bat, for f
max, acceleration will be higher and the speed at which you hit the ball will therefore be higher.
What none of this theory covers is your ability to hit the ball however. If you have a lighter bat, you will be able to swing the bat faster, but more importantly, you will also be able to control the swing better as you will require less force (strength) to adjust the path of the bat (which is a function of acceleration).
This therefore goes back to the comment made earlier that when pitches are less reliable in terms of bounce and predictability, a lighter bat is required to allow the batsman to control their shot playing dependent on bounce.