How fast is a particle of 173kg moving if it has 960J of energy?

Question

ganeshie8 · Answer

use kinetic energy formula

ganeshie8 · Answer

$\large KE = \frac{1}{2} mv^2$

doc.brown · Answer

$$E_{K}=\frac{1}{2}mv^2$$$$v=\sqrt{\frac{2E_{K}}{m}}$$$$v=\sqrt{\frac{2(960J)}{173kg}}$$$$v=3.3\frac{m}{s}$$$$3.3\frac{m}{s}\times\frac{3.6km\cdot s}{m\cdot h}=12\frac{km}{h}$$Is this right?

ganeshie8 · Answer

3.33 m/s is correct, 
after that... if ur arithmetic is correct, it shud be correct :)

ganeshie8 · Answer

btw, why we're ignoring PE ?

doc.brown · Answer

I wanted to see how fast a heavier particle would have to go to have the same energy as 12g at 400m/s.
Why?  What would you do with potential energy?

ganeshie8 · Answer

okay, total energy = PE+KE

ganeshie8 · Answer

$\large \frac{1}{2} m_1v_1^2 = \frac{1}{2} m_2v_2^2$

ganeshie8 · Answer

if you knw the masses, you can find the velocity