Question:

A .0541 kg bullet is fired into a 3.25 kgblock on a ballistic pendulum. The bullet goes straight through the block (without changing the mass of either object) and exits with the speed over 183 m/s. The block rises to a maximum height to .177 meters. What was the initial speed of the bullet?

Raw Transcript

Hello, everyone. Tom from everystepphysics.com and everystepcalculus.com. Physics test problem. A .0541 kilogram bullet is fired into a 3.25 kilogram block on a ballistic pendulum. The bullet goes straight through the block (without changing the mass of either object) and exits with the speed over 183 meters per second. The block rises to a maximum height to .177 meters. What was the initial speed of the bullet? Let’s do it in my program see how that works. Physics to get to my menu. We’re going to scroll down to all alphabetical, down to bullet pendulum. And this is a bullet going through the block so we choose number two. You can use the numbers before this . And we want to find the initial velocity at the bullet, number two. It asks you if the height is given. Yes, it is. We’re going to choose number one. We’re gonna enter the mass of the bullet. You have to press Alpha before you enter anything in these lines here. Alpha .0541 kilograms. Mass of the block is Alpha 3.25 kilograms. The height is Alpha .177 meters. Choose number two. And the final velocity is Alpha 183 meters per second, number four. It’s in the easterly direction so we’re going to use that one. I always show you what you’ve entered. You can change it if you want if there’s been a mistake. I say it’s okay. We need to find the the final velocity of the block first which is 1.8635. Do this formula, here. Square root of 2 GH. Enter the variables. Here it is. And here’s the formula for finding the initial velocity of the bullet. Here’s the added the variables and here’s the answer 294.95 meters per second. Pretty neat, huh? everystepphysics.com. Go to my site, buy my programs. Thank you.