A shell is fired horizontally and takes .5 seconds to fall. If its initial speed were doubled, the time it would take to fall would be:

.25 seconds

I know the answer, but I need an explanation if possible.

6 answers

Your answer is not correct.
Then what is the correct answer?
When the shell is fired horizontally, it has no vertical component. The vertical speed is 0. Gravity eventually pulls it to earth. If you double the horizontal speed, you still have no vertical component. Therefore, the time to fall is?
double?
If there is no vertical component, then the time to fall to earth is just a function of the height above ground. The shell always takes the same time to fall to the ground. If you double the initial speed of a horizontal shot, it still takes the same time before it strikes the ground. With the doubled speed the shell will travel farther, but the time to hit the ground is the same. If it was 0.5 seconds on the first shot, it will still be 0.5 seconds.
I understand now, thanks.