momentum and collisions

Question

A bullet is accelerated down the barrel of a gun by hot gases produced in the combustion of gun powder.

m = 0.0295 kg

v = 610 m/s

t = 2.25 ms

a) what is the magnitude of the average force exerted on a bullet of mass m, to accelerate it to a speed v, in a time interval of t? F ave=

b) what is the magnitude of the average force, in newtons, if the bullet has a mass of 0.0295kg and the gun accelerates it to a speed of 610 m/s in a time of 2.25 m/s

Answer 1

Hi Lauren,

It seems to me that parts (a) and (b) are asking the same question . . . so let me see if I can help.

The equation for Newton's 2nd Law can help us. It says that F = ma. We are looking for average force, right!

If we replace acceleration by (change in velocity) divided by (change in time), then the equation becomes

F = mv/t

Substitute your given information into this equation to find your average force! You should get close to 8000 N. Watch out for the common error though --> your time is given in milliseconds. Convert it to seconds first by moving the decimal three places to the left!

Hope this helps!

Jim