Physics Test Solved on TI-89 App | Bullet’s Speed Video

January 6, 2014 · by physics · Bullets, Momentum, Physics Test Questions

A miniature spring-loaded, radio-controlled gun is mounted on an air puck. The gun’s bullet has a mass of 5.00 g, and the gun and puck have a combined mass of 120 g. With the system initially at rest, the radio controlled trigger releases the bullet horizontally causing the puck and empty gun to move with a speed of 0.500 m/s. What is the bullet’s speed?

a. 4.80 m/s
b. 11.5 m/s
c. 48.0 m/s
d. 12.0 m/s

 Raw Transcript

Hello this is Tom for every step physics dot com I’m gonna do actual test problem number seven on the sheet here which I’ll show you the problem and let’s get started you go to my main menu and because you know it’s a collision problem our momentum problem you’re going to scroll down to a collision
if you didn’t know it was that you and you thought it was momentum you would go to momentum and it’d take you to the same spot but and this one here decides certain words in a problem to see whether it’s a momentum problem or a collision problem in this case number seven says is what releases scroll down to that thing that separates momentum problems from collision problems that the two masses are at rest at the beginning so they can’t collide so just a little information there
and we’re gonna find the bullets final velocities so we’re join to choose final velocity of mass 2 we’re gonna enter mass 1 which is you have to press Alpha before you enter anything in my programs Alpha 120 and it says gram so we’re gonna choose grams a show you how to convert that put that on your paper and
the bullets mass is 5 grams does a quick conversion and the releasing velocity is alpha .5 meters per second and because we’re releasing or pushing you have to you push off to the left if you were it was happening in reality and you push to the right so our velocity is gonna go to the left which is number two
becomes a minus and I check and see if tell you show you so that you can see if you’ve entered the right stuff or if you are happy with it I say it’s okay and momentum is p1 is the momentum of mass one which is the gun and the puck an that’s the mass times the velocity so it’s minus .06 kilograms per meters per second and because one of the rules in physics P one plus p2 equals zero we have the p1 is minus .06 so that becomes a a positive number for p2 because they’re equal and then we can figure the final velocity
of the bullet which is 12 meters per second pretty neat huh, every step physics dot com