An object has a mass of $9 kg$ . The object's kinetic energy uniformly changes from $135 KJ$ to $36KJ$ over $t in [0, 6 s]$ . What is the average speed of the object?

Question

1849 views around the world

You can reuse this answer
Creative Commons License

Answer 1 · 2016-04-19T16:47:08

I don't produce any number as the result, but here is how you should approach.

$KE = 1/2 mv^2$

Hence, $v = sqrt((2KE)/m)$

We know $KE = r_k *t+c$ where $r_k = 99KJs^(-1)$ and c = $36KJ$

So the rate of change of velocity $r_v$ is related to the rate of change of kinetic energy $r_k$ as:

$v = sqrt((2r_k*t +2c)/m)$

now, average velocity should be defined as:

$v_"avg" = (int_0^t vdt)/t= 1/5int_0^5 sqrt((2r_k*t +2c)/m) dt$

An object has a mass of 9 kg9 kg. The object's kinetic energy uniformly changes from 135 KJ135 KJ to 36KJ 36KJ over t in [0, 6 s]t in [0, 6 s]. What is the average speed of the object?