Question

A stone is dropped into a deep well and is heard to hit the water 3.41 s after being dropped.

a) Determine the depth of the well. Show your work.
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b) How fast is the stone travelling right before it hits the water? Show your work.
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c) Assume that the stone is being dropped on Planet X, where the magnitude of the acceleration due to gravity is less than that on Earth. Would the velocity of the stone right before it hits the water be greater than, less than or the same as the value from part b)?
____ Greater than ____ Less than ____ The same as
Explain your reasoning.
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Answer 1

Answer:

a) Given, acceleration of stone is a=g=9.8m/s²

Initial velocity is u=0m/s

Time for hitting water is t=3.41s

If d be the depth of the well. 

Using d=ut+at²÷2,

∴  d=0(3.41)+0.5(9.8)(3.41)²=56.98∼57m

b) There are 3 equations of motion which are used to study the objects moving with a constant acceleration.

The acceleration is defined as the rate of change of velocity. So if the velocity is changing with a constant rate then the acceleration is taken as a constant value. Equations of motion can be applied in the case of free fall of an object. In the case of free fall the gravity is the deriving factor leads to a constant acceleration due to gravity.