What factors determine the speed of a projectile fired from an air gun?

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    Projectile Speed
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Discussion Overview

The discussion revolves around determining the speed of a projectile fired from an air gun. Participants explore various methods to measure this speed, considering factors such as distance, time, and projectile weight. The context includes practical experimentation and calculations related to projectile motion.

Discussion Character

  • Exploratory
  • Technical explanation
  • Homework-related

Main Points Raised

  • One participant seeks a formula to calculate the speed of a projectile, given its weight, distance, and the gravitational pull of Earth.
  • Another suggests a method involving timing the sound of impact to measure speed, using the formula s=d/t, while noting the need to account for the speed of sound.
  • A participant humorously questions the safety of having a friend stand near the target due to the projectile's power.
  • Some participants propose measuring the impact force and distance to refine their calculations, indicating that the air gun may shoot farther than initially considered.
  • One participant suggests using a foam board to measure the drop distance of the projectile to calculate time and then speed, but expresses concern about the accuracy of this method.
  • Another reiterates the foam board method, emphasizing the need for accurate shooting and multiple trials for reliable results.

Areas of Agreement / Disagreement

Participants do not reach a consensus on a single method for measuring projectile speed, with multiple competing approaches and concerns about accuracy and safety being raised throughout the discussion.

Contextual Notes

Some methods proposed depend on assumptions about the projectile's behavior and the accuracy of measurements, which remain unresolved. The discussion also highlights potential limitations in the experimental setups suggested by participants.

lolomolo
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I got an air gun and i need to find how fast (m/s) it fires a projectile. If i knew speed (s) the distance when it hits the ground (d) and the weight of projectile (10g) and the angle is horizontal zero degrees (0*) i know Earth has a (9.8m/s) gravity pull so what els do i need to know and could you write me a formula to follow? Ty ; )
 
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you could do something simple like have a friend stand next to you and fire at a metal can like 100 meters away or 70 or what ever you can hit further the better , and count down to when you pull the trigger and then stop the watch when you hear the ping.
using s=d/t , and you might want to factor in the time lag for the ping at the speed of sound 343 m/s
 
um easy? this thing shoots projectiles that blow holes in concrete slabs I am sure "some friend" is going to stand there. meat shield much?
 
and plus if i shoot only 100m I am also going to find the impact force because I am prety sure it shoots much farther
 
ok I thought of another way . take a piece of foam board and place it 50 meters or so away , and aim at the top of the board then you can see where the bullet went through and you can measure this distance from the top and using d=1/2gt^2 you can calculate how much time it took the bullet to drop and then do s=d/t because you know the distance is 50 meters or how ever far you want to shoot it from , this may take some accurate shooting and a couple of trials but it should work.
 
Last edited:
cragar said:
ok I thought of another way . take a piece of foam board and place it 50 meters or so away , and aim at the top of the board then you can see where the bullet went through and you can measure this distance from the top and using d=1/2gt^2 you can calculate how much time it took the bullet to drop and then do s=d/t because you know the distance is 50 meters or how ever far you want to shoot it from , this may take some accurate shooting and a couple of trials but it should work.

thought of that but its not that accurate it shoots 2 in airsoft granade shells or AA bateries
 

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