If you drop a 1.36 kg weight and it falls .1524 meters, what is its velocity when it hits the ground and how is this calculated. Ultimately I am trying to decide how much energy is released.

Thanks,

Greg

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- December 21st 2005, 03:23 AMGreg Evelocity of falling object
If you drop a 1.36 kg weight and it falls .1524 meters, what is its velocity when it hits the ground and how is this calculated. Ultimately I am trying to decide how much energy is released.

Thanks,

Greg - December 21st 2005, 12:45 PMCaptainBlackQuote:

Originally Posted by**Greg E**

constant acceleration of the minus sign is conventional as

up is normally taken as positive, and so downward accelleration is negative.

So , and if the initial speed is then .

Integrating again gives:

,

where is the initial height of the weight, for convenience we will

take this to be .

Now we are interested in what is happening when the weight has fallen

. This occurs when:

,

or:

.

Putting this back into the equation for vertical velocity:

.

At the earth surface .

We could have short circuited this calculation by knowing that the change

in potential energy when the weight drops through a height is

,

which will equal the kinetic energy of the weight when it has fallen from rest

through a distance :

RonL