Question

A bullet weighing 235 grains is moving at a speed of 2.52 X 10^3 ft/s. Calculate the kinetcic energy of the bullet in joules ahd in calories. One grain equals 0.0648 g.

Can someone help me out on this please

K. E.= 1/2 mv2 .
Convert m to kg
Convert ft/sec to meters/second.
Then KE you obtain is in Joules. There are 4.184 J in 1 calorie.

What is mv???

Answer 1

m = mass
v = velocity (speed in your problem).
K. E. = kinetic energy.
You will need to convert 236 grains to grams (the conversion factor is in the problem), convert grams to kg. Then just plug in m and v.

Answer 2

235 grains (0.0648 g/ 1 grain)(1000 kg/1 g)=
2.52 X 10^3 ft/s (1 m/3.28 feet)=

is this the correct set up then where do i go from here

Answer 3

235 grains*(0.0648 g/1 grain)*(1 kg/1000 g) = ?? kg.
<b>Note: the conversion from grains to g is correct. BUT, there are 1000 g/1 kg and not 1000 kg/g.</b>
The indicated work for ft/s to m/s is correct.
So you have mass in kg, you have velocity in m/s, multiply them, take 1/2 of that and you have K. E. in joules.

Answer 4

Just a note to clarify the above. Of course you must remember to square the v before multiplying by m and taking 1/2.

Answer 5

A bullet weighing 245 grains is moving at a speed of
2.52  103 ft/s. Calculate the kinetic energy of the bullet in
joules and in calories.