Scientists have investigated how quickly hoverflies start beating their wings when dropped both in complete darkness and in a lighted environment. Starting from rest, the insects were dropped from the top of a 50 - cm tall box. In the light, those flies that began flying 200 m s after being dropped avoided hitting the bottom of the box 87 % of the time, while those in the dark avoided hitting only 25 % of the time. Required:
a. How far would a fly have fallen in the 200 ms before it began to beat its wings?
b. How long would it take for a fly to hit the bottom if it never began to fly? In seconds.

Explanation:

a )

Hoverfly will fall with acceleration equal to g .

Initial velocity of fall of hoverflies u = 0

displacement ( vertical ) h = ?

time t = 0.2 s

acceleration due to gravity g = 9.8 m / s²

h = ut + 1/2 g t²

= 0 + .5 x 9.8 x .2²

= .196 m

= 19.6 cm

b )

Time taken to fall by 50 cm or 0.5 m under free fall from initial position .

.5 = 0 + .5 x 9.8 t²

t² = .1020

t = .319 s = 319 ms .

what type of charge does it have? negative

the skeletons of most mammals reach a certain size and then stop growing. however, many animals, including some mammals, keep growing throughout their lives. kangaroos, for example, just keep growing and growing until they die. also, the longer an animal lives the greater the chance it might catch some deadly disease.