Posted by Danielle on .
A person stands on a bridge that is 100 feet above a river.
If she drops a pebble how fast is it moving after 2 seconds?
How long does it take the pebble to reach the river below?
She has another pebble that she tosses up with initial speed of 8 feet per second. It goes up, then starts falling down to the river below. By the time it reaches the river what is its speed?

calculus HELP! 
bobpursley,
Calculus? Hardly.
vf=vi+gt for the firstquestion
second question: h=vi*t4.9t^2 Vi=0, solve for t
third question
hf=hi+vi*t4.9t^2
0=100+8t4.9t^2
solve for time t, then vf=vi9.8t
but there is an easier method for the last:
vf^2=vi^2+2ad where a=9.8, d=100