how do I solve this word problem?

Question

You drop a pencil out a window that is 20ft above the ground. Use the formula V² = 64s, where V is the speed and s is the distance fallen, to calculate the speed the pencil is traveling when it hits the ground.

Answer 1

Hi Syd,

 

We need to solve for V when s is 20ft:

 

V²=64s

V = sqrt(64s)  (we can ignore the negative square root, our answer should be a positive speed)

V = sqrt(64*20) = 8*2*sqrt(5) = 16*sqrt(5)

 

V = 16 sqrt(5) or V is approximately 35.777 ft/time