Question

What is the kinetic energy of an object with a mass of `3 kg` that has been in freefall for `6 s`?

Answer 1

I found `5,186J`

Explanation:

the object will fall from a height given as:
`y_f-y_i=v_it+1/2at^2`
where:
`y_f=0` the ground;
`y_i=h` is the height from which the object is falling;
`v_i=0` the initial velocity;
`t` is the time;
`a` is the acceleration of gravity.
We then get:
`-y_i=-1/2*9.8*(6^2)`
so `y_i=176.4m`
When the object falls potential energy `U=mgh` is converted into Kinetic Energy `K`.
so::
`U=3*9.8*176.4=5,186J` that will be our kinetic energy.