6. A cannon with a long barrel fires a shell faster because the shell experiences a greater ____________________.

A) change in inertia.
B) impulse.
C) acceleration.
D) None of these.

force lasts longer

impulse = force * time = change of momentum
longer time --> more impulse

The correct answer is C) acceleration.

To understand why acceleration is the correct answer, let's break down each option and determine which one relates to a cannon firing a shell faster.

A) Change in inertia: Inertia is the tendency of an object to resist changes in its motion. A larger object may have a greater inertia, but it does not explain why the shell is fired faster. So, this option is not the correct answer.

B) Impulse: Impulse refers to the change in momentum of an object and is measured by the product of force and the time over which it acts. While the impulse can affect the speed of the shell, it doesn't explain why it is fired faster. So, this option is not the correct answer.

C) Acceleration: Acceleration is the rate at which an object changes its velocity over time. When a cannon fires a shell, it propels the shell by rapidly accelerating it in the barrel. This acceleration imparts a greater speed to the shell, causing it to be fired faster. Therefore, this option is the correct answer.

D) None of these: Since we have identified that option C) acceleration is the correct answer, option D) can be eliminated.

In summary, the cannon with a long barrel fires a shell faster because the shell experiences a greater acceleration.