🎉 Announcing Numerade's $26M Series A, led by IDG Capital!Read how Numerade will revolutionize STEM Learning Numerade Educator ### Problem 73 Easy Difficulty # A soldier on a firing range fires an eight-shot burst from an assault weapon at a full automatic rate of 1000 rounds per minute. Each bullet has a mass of 7.45$\mathrm{g}$and a speed of 293$\mathrm{m} / \mathrm{s}$relative to the ground as it leaves the barrel of the weapon. Calculate the average recoil force exerted on the weapon during that burst. ### Answer ## 36.4$\mathrm{N}\$

#### Topics

Moment, Impulse, and Collisions

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##### Christina K.

Rutgers, The State University of New Jersey

##### Andy C.

University of Michigan - Ann Arbor

##### Marshall S.

University of Washington

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### Video Transcript

Okay, so we have this data a solve their, uh, fires a weapon. Okay. It's a full automatic rate off 100 rounds per minute. Okay, We know that the mass off each bullet is 7.45 g. Okay, I'm going toe convert this 2 kg. So this is 7.45 times 10 to the minus 3 kg. Okay? And we know the speed off each bullet. Okay, so we want to calculate the average recalled for us. Okay, so by nettles, Arthur Lowe. Okay. Imagine this is the waffle. I know. It's a good he would you know that the average force the weapon exerts on the bullet. Okay, so the first the weapon exerts for the bullet to come out, it's equal in magnitude on opposite direction. So we have another force like this, okay to the recall force that the bullet exert on the weapon. Okay, so we have This is not the ones. There are a lot. Okay, so we want to find this one. So you actually see it's the same as if we'll find this one is just about fine. OK, but the magnitude it's the same on for this we use or we think that the average force Okay. Yes. The what? Supply right time. Okay, but by an interval in time, it's equal. Thio the momentum. Right? So if I want to find the for us, okay, I just have a moment, um, divided by time. Okay, so, uh, I know mo mentum is, uh, mass Times velocity. Okay. And the mask off the woman onto the minus 3 kg. Right? I know the speed three Serena 200 is, uh, 293 m per second. Okay, but since I'm finding the average, I know that I have 100 good, wrong parent minutes, and I know that one minute it's 60 seconds. Why? It's like if I find this for just one bullet. Mhm. But it's actually eight. So it since its average is the same as funding as finding it for one for eight for one million. And this is, uh because all the bullets have the same value. Okay, Ana, if you make this calculation, this is 36.4 newton. So the average recoil force is 36.4. Yeah,

Universidad Nacional Autonoma De Mexico UNAM- San Antonio

#### Topics

Moment, Impulse, and Collisions

##### Christina K.

Rutgers, The State University of New Jersey

##### Andy C.

University of Michigan - Ann Arbor

##### Marshall S.

University of Washington

Lectures

Join Bootcamp