What is the kinetic energy of an object with a mass of $5 kg$ that has been in freefall for $4 s$ ?

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Answer 1 · 2016-04-08T01:20:14

About $4000J$

In freefall, I assume acceleration due to gravity, $g$ is $10ms^-2$ .

$g=(v-u)/t$
We need to find the final velocity $v$ . We know that the initial velocity $u=0$ and $t=4s$
$g*t=v$
$10ms^-2*4s=40ms^-1$

Kinetic energy is $1/2mv^2=1/2*5kg*(40ms^-2)^2=4000J$

What is the kinetic energy of an object with a mass of 5 kg 5 kg that has been in freefall for 4 s 4 s?