In a ballistics test, a 28-g bullet pierces a sand bag that is 30 cm thick. if the initial bullet velocity was 55 m/s and it emerged from the sandbag moving at 18 m/s what was the magnitude of the friction force (assuming it to be constant) that the bullet experienced while it traveled through the bag?

Frictional force will be equal to 126.04 N

Explanation:

We have given mass of the bullet m = 28 gram = 0.028 kg

Initial velocity u = 55 m /sec

Width of sand = 30 cm = 0.3 m

So initial kinetic energy

Final velocity of the bullet v = 18 m /sec

So final kinetic energy

So change in kinetic energy = 42.35 - 4.536 = 37.814 j

From work energy theorem this change in kinetic energy will be equal to work one by frictional force

So

waves moving from a fast medium to a slow medium will experience a reflection as light travels more slowly than red light. total internal reflection occurs when the critical angle is.

hi there!

out of the two, (b) precision would be more reasonable.   however, both a and b could be pretty reasonable.

-awesomerepublic   : )