Question 211170
 A punter can kick a football with an initial velocity of 48 feet per second. How many seconds will it take for the ball to return to the ground?(Hint: Use the formula h=vt-16t2*)I was unsure whether or not this formula was correct for some reason I thought the formula was h=v-16t2*.
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It can't be h=v-16t^2, because the units don't match.
h = distance and v is speed.  You can't add and subtract feet and feet/sec.
Multiplying v*t gives feet/sec x 1/sec = feet.
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h=48t-16t^2
The ground is h = 0
48t - 16t^2 = 0
t*(48 - 16t) = 0
t = 0 (at the start)
t = 3 (return to the ground)
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BTW, the -16t^2 term is acceleration due to gravity.  It's (gt^2)/2, where g is -32 ft/sec/sec.  
Muliplying ft/sec/sec by sec^2 gives feet, so the units are uniform.