What is the Kinetic Energy of Bullets Fired at Different Speeds?

Thread starter PepeF.
Start date Nov 14, 2009
Tags

Energy Kinetic Kinetic energy

AI Thread Summary

The discussion focuses on calculating the kinetic energy of two bullets with masses of 3.5 grams, fired at speeds of 42.4 m/s and 69.6 m/s. The kinetic energy formula used is EK=(1/2)mv^2, but the initial calculation was incorrect due to not converting the mass from grams to kilograms. After correcting the mass to 0.0035 kg, the kinetic energy for the first bullet was calculated to be approximately 3.14 Joules. The correct approach emphasizes the importance of unit conversion in physics calculations. The thread highlights the significance of accuracy in applying formulas to achieve correct results.

Nov 14, 2009

PepeF.

Homework Statement

two 3.5g bullets are fired with speeds of 42.4 m/s and the 2nd one with 69.6 m/s

what is the kinetic energy of the first bullet?
the second one?

Homework Equations

EK=(1/2)mv^2

The Attempt at a Solution

EK=(1/2)3.6*42.4^2 = 3235.968

it is wrong.. why?

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Nov 14, 2009

mgb_phys

Science Advisor

Homework Helper

units

Nov 14, 2009

JakePearson

you have not converted the mass of the bullet from grams to kgrams

0.50 x (3.5x10^-3) x 42.4^2 = 3.14J

this is the answer i got

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