# Physics

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Two bullets have masses of 2.4 g and 5.2 g, respectively. Each is ﬁred with a speed of 37.0 m/s.
a) What is the kinetic energy of the ﬁrst
bullet?
b) What is the kinetic energy of the second bullet?

I initially used KE=1/2MV^2 and got 1642.8 J, but got it wrong. What is my mistake?

• Physics -

Mass is measurd in kg Not grams. S0 you
must convert to kg:

divide grams by 1000.

• Physics -

I see! Thank you!

• Physics -

Another quick question, what is the ratio
K2/K1 of their kinetic energies. Is, it just dividing the second bullet's KE to the first?

• Physics -

The ratio of K2 to K1 = K2/K1.
The ratio of K1 to K2 = K1/K2.

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