It takes 6 seconds for a stone dropped from rest to hit the bottom of a well. What is its final speed?

Question

Question: It takes 6 seconds for a stone dropped from rest to hit the bottom of a well. What is its final speed?
a. 6 meters/second
b. 30 meters/second
c. 36 meters/second
d. 60 meters/second

Answer 1

v^2 = 2gh

h=1/2 gt^2

subs this.
v^2 = 2g (1/2 gt^2 )
v^2 = 2 g^2 6^2
v^2 = 100 X 36

v= 60m/s

Answer 2

Assuming that the well is doesn't hold water or bottom means when it hits the water surface. If this question is not of reasoning, in which case the final speed will be 0 as the stone will come to rest, then the speed depends on the resistance it suffers from the air. In ideal condition only the force of gravity will act upon it and you can get the answer by using newton's first law which is v = u + at.

Here :
u(initial velocity) = 0 as the stone is dropped from rest
t = 6 sec
a = 9.8 m/s
v (final velocity) = 0+ (9.8*6) = 58.8m/s.

Also we usually takes g = 10m/s in which case the final velocity will be
v = 0 + (10*6) = 60 meters/second (option d)

Answer 3

There is no where close to enough information to give you a viable anwser. Is the stone going through liquid on its way down to the bottom (i.e. water, plasma, jello)? What is the mass of the stone being dropped? What is the reference area of the stone? Is the at sea level and what is the barometric pressure if this is in air?
For a basic estimate by the given data you can state
a=v/t
v = 9.8m/s^2 * 6 secs = 58.8 m/s
but this doesn't account for air resistance and the possiblity of the stone hitting terminal velocity.

If instead you mean once the stone comes to the bottom, this can not be calculated either with your information. Stating zero is very inaccurate. Once the stone hits the bottom of the well (whether filled with liquid or not), the stone will have a temporary acceleration upward due to the bottom of the well inacting a force to counter the force of the falling stone. So basically, the stone will bounce.

Answer 4

Acceleration due to gravity is ~9.8m/s^2 at sea level. Thus any object falling for 6 seconds will have 6 seconds worth of acceleration, or about 6 x 9.8m/s = 58.8m/s velocity barring any resistances such as atmospheric. The closest selection would be (D) 60 meters/second.

This assumes of course that you mean the instantaneous speed as it hits the bottom. If you mean its final speed as/after it hits, that would of course be zero since it stopped at the bottom. But zero was not one of the choices provided.

Answer 5

125

Answer 6

It is 0 meters/second.

Answer 7

attempt to no longer use numbers that haven't any relevance to the question. this might reason confusion. at the same time with 4 instead of for, and a pair of instead of to. Maths & Physics desires clean expositions.

Answer 8

The answer is d. 60 m/s,

speed = acceleration * time

speed = 9.81 m/s^2 * 6s

speed = 58.86 m/s

approximately 60 m/s

Answer 9

acceleration due to gravity = -9.8 m/sec^2

velocity = -9.8 t + initial height (which is 0)

So after 6 sec. v = -9.8 x 6 = 58.8 m/s

so d is closest

Answer 10

You would need to know if there was water in the bottom.