That’s not enough to seriously hurt someone, is it? (Ergo, NERF guns are totally safe.) Here’s the graphical representation of the data. For a constant velocity, if the mass is doubled, the energy is doubled however. The results? For the one shot, he got an initial velocity of 8.73 m/s. The velocity of the bullet is a more important determinant of muzzle energy. Analysis came after, to determine launch speeds and other physic-ky data. Let’s just talk about Allain’s report for the sheer fun of it!Īrmed with a belt-fed NERF gun (naturally), a video camera, and Tracker Video (for analysis), he had some fun shooting the gun. Then again, figuring out the safety issues should be done by the designers and testers as Hasbro. With the guns getting bigger and more complicated (some spewing out bullets in quick succession), there is a practical application for Allain’s study. We were then able to use the velocity of the bullet and the conservation of momentum to calculate the muzzle velocity of the BB. While we all know that NERF guns just might be the safest – not to mention most fun – toy guns there are, I am sure that there are parents out there who still have safety concerns. So to calculate the Velocity of the BB + pendulum we derived the equation: velocity 2gravityheight swung by the pendulum. I guess that will be a post for another day.Anyhow, with countless people having fond memories of NERF (not to mention people who continue to create new encounters with the toys), I thought it was brilliant that Rhett Allain of Wired (( Source)) conducted his own study regarding the physics behind NERF bullets. I am pretty sure that plain balls would have a fairly constant vertical acceleration. I guess what I really need to do is to toss a whole bunch of balls and find the accelerations. After looking at more motions of bullets, I am going to go with the aerodynamic instabilities as a major contributor to the variation in the accelerations. So, overall the acceleration wasn't too bad. This gives an average vertical acceleration of -9.60 m/s 2 with a standard deviation of 0.72 m/s 2. Here is a histogram of the acceleration data. Really, if you look at the video closely, you will see these Nerf bullets are not very stable in flight. This is small compared to the standard deviation of the x-velocities. What would the x-velocity be for this case? citation needed The momentum delivered to the target, however, cannot be any more than that (due to recoil) on the shooter. Suppose I have an actual launch speed of 10.4 m/s, but I shoot it 2.6 degrees above the horizontal. From the viewpoint of physics (dynamics, to be exact), a firearm, as for most weapons, is a system for delivering maximum destructive energy to the target with minimum delivery of energy on the shooter. It seems that the barrel of the Nerf gun goes from a minimum of -1.1 degrees below the horizontal to 2.6 degrees above. Ok, but what about the variation in the gun angle? Is that what could cause the variation in the launch speeds (since I am really just measuring v-x)? Good question. Sure, I could do some statistical tests, but I am going to stick with the eyeball. This is the distribution of the x-velocities (which I am assuming to the be the initial velocity). What happens if I find the acceleration and the initial velocity for two belts worth of darts? Here is what you get. So, for this shot I will say that it was shot horizontally and has an initial velocity of 8.73 m/s. Either that, or I video recorded this in the middle of a gravity wave that LIGO failed to detect. A bullet of mass 50 g moving with an initial velocity 100 m s-1 strikes a. The only thing I can think of is that there is some sort of aerodynamical thingy happening. Also, I am pretty sure the axis is set so that y is in the vertical direction. I am pretty sure my video is scaled correctly. The bad thing is that it is a bit too large (or larger than expected) with a value of around -10.2 m/s 2. The good thing is that the acceleration looks fairly constant. The initial velocity of the ball is determined by shooting it, at the appropriate angle, through 2 photogates that are placed near the muzzle and only a few. This seems like a fairly constant slope of 8.73 m/s. If the air resistance was a significant factor, the slope of the line (the x-velocity) would decrease as time increased. A linear function suggests that there is negligible air resistance.
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