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Pendulum hit with Bullet-Video

February 3, 2015 · by physics · Bullets, Velocity in Physics

Question:

A pendulum consists of a 2 kilogram block hanging on a 1.5 meter
length of string. A ten gram bullet moving with a horizontal velocity of nine hundred meters per second strikes passes through and emerges from the block which was initially at rest with the horizontal velocity of three hundred meters per second. To what maximum height above its initial position will the block hang?

Transcripts

Hello, everyone. I’m Tom for everystepphysics.com and everystepcalculus.com. I’m going to do physics problem here. I’m going to read it right now. A pendulum consists of a 2 kilogram block hanging on a 1.5 meter length of string. A ten gram bullet moving with a horizontal velocity of nine hundred meters per second strikes passes through and emerges from the block which was initially at rest with the horizontal velocity of three hundred meters per second. To what maximum height above its initial position will the block hang? So let’s do it and show you how my programs work on this. You enter physics here to get to my main menu. We’re going to scroll down to bullet and pendulum. Which is right. And we’re going to enter our variables. You have to press enter before you enter anything in these entry lines here. So it asks to enter mass so we’re going put Alpha 3 and grams. I show you how to convert that to meters. And second mass is Alpha 2 kilograms. Initial Velocity is Alpha 1000 meters per second. And this is at Alpha 0 because the block is a rest hanging. And then we’re going into the final velocity is the bullet passes through Alpha 300 meters per second. And given in the positive direction east. Enter length of string is Alpha 1.5. I don’t know what they gave that to you in a problem for because it’s not entered into the calculations so must be to throw you off or something which professors love to do. This is at meters. So, I show you what you’ve entered, you can change it if you want. I say it’s okay. And it’s asking for the height so we’re going to choose number 3 here. And you have to find the velocity first. Which is .75 meters per second squared. I mean per second meters per second. And then we use that velocity to find the height which is .02867 meters. Centimeters would be .029 close to the 27 centimeter answer And that’s what you’d circle and get a 100 percent in this problem. You can choose 2 also and get to the and find the actual velocity of the block. Which is .75 meters per second. Pretty neat, huh? everystepphysics.com. Thank you.