Acceleration Due to Gravity

[thegreatone09]

A ball is thrown up into the air and it passes a certain window 0.3s after being released. It passes the same window on its way back down 1.50s later. What was the intial velocity of the ball?
Any help will be appreciated.

[WhiteKnight]

Ask yourself what the total flight time of the ball was.

[Pandemonium]

Here's a simple hint I can give: if resistance is ignored, then the upward motion is 'symmetrical' to the downward motion.

[rdecker]

If you haven't got it by now the total time is 0.3 +1.5 + 0.3 = 2.1 s. Since the velocity is zero at it's maximum height you can divide the time in half to find how long it takes the ball to fall from its maximum height to the ground. Then use that time to calculate distance and then final velocity.