Posted by **Danielle** on Wednesday, November 6, 2013 at 9:45pm.

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**, Wednesday, November 6, 2013 at 9:53pm
Calculus? Hardly.

vf=vi+gt for the firstquestion

second question: h=vi*t-4.9t^2 Vi=0, solve for t

third question

hf=hi+vi*t-4.9t^2

0=100+8t-4.9t^2

solve for time t, then vf=vi-9.8t

but there is an easier method for the last:

vf^2=vi^2+2ad where a=-9.8, d=-100

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