Posted by Michael on .
A 70.0 kg football player leaps straight up into the air (with no horizontal velocity) to catch a pass. He catches the 0.430 kg ball precisely at the peak of his jump, when he is 19.2 inches off the ground. He hits the ground 1.61 inches away from where he leapt. If the ball was moving horizontally when it was caught, how fast was the ball travelling?

Physics HW, Help Please 
drwls,
Compute the time it takes the player to hit the ground after catching the ball. Call it t.
t = sqrt(2H/g) = 0.315 seconds
The horizontal velocity acquired after catching the ball is 1.61/t inches per second or 0.1342/t ft/s = 0.426 ft/s. Call that Vx.
Use conservation of horizontal momentum for the velocity v of the ball when caught.
v*0.43kg = (70.43 kg)*Vx