Suppose a rock is dropped into a well 9.8 meters deep. a) determine the amount of time t it takes for the rock to hit the bottom of the well. t = incorrect: your answer is incorrect. b) determine the velocity v of the rock as it is hitting the bottom of the well. v = c) if the bottom of the well is lined with thick sand so that the rock does not bounce, what is the velocity vf of the rock just after it hits the bottom of the well? vf =

a) t=1.41 sec

b)13.8m/s

c) 0 m/s

Explanation:

a) We use the formula of  Motion with constant acceleration:

Where:

g= gravitational acceleration

t=time

y=9.8meters

We isolate t from equation and solve:

t=1.41 sec

b) Velocity at the bottom of the well can be determined by expression:

c) vf= 0 m/s The sand absorbs the potential energy of the rock, so its final velocity after hitting the bottom of the well will be 0 m/s.

when insulating materials rub against each other, they may become electrically charged . electrons , which are negatively charged, may be 'rubbed off' one material and on to the other. the material that gains electrons becomes negatively charged. the material that loses electrons is left with a positive charge.

wavelength divides in half and speed stays the same.