What Causes the 40 Ton Recoil in a 120mm Mortar?

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Discussion Overview

The discussion centers around the recoil force of a 120mm mortar, specifically questioning what is meant by the stated 40 tons of recoil. Participants explore the context of this measurement, including whether it refers to the reaction force from gases or the force transmitted to a platform or vehicle. The conversation also touches on units of measurement and conversions between tons, pounds, and Newtons.

Discussion Character

  • Debate/contested
  • Technical explanation
  • Mathematical reasoning

Main Points Raised

  • One participant asks whether the 40 tons of recoil refers to the reaction force from gases or the transmitted force to a vehicle.
  • Some participants assert that both interpretations are valid depending on the context.
  • There is a discussion about the use of tons as a non-SI unit of force, with references to conversion factors.
  • One participant mentions the variation of gravitational acceleration (g) and its negligible effect on the recoil force.
  • A later reply questions the relevance of the angle of inclination (60 degrees) in the context of recoil.
  • Another participant clarifies that a ton is equivalent to 2000 pounds and discusses the conversion to Newtons as the desired SI unit.
  • Participants engage in a debate about the nature of pounds as a unit of force and the implications for measuring weight, with some expressing frustration over the direction of the conversation.
  • One participant references the conservation of momentum to relate the mortar's mass and speed to the recoil force, providing a calculation that converts 40 tons to Newtons.

Areas of Agreement / Disagreement

Participants do not reach a consensus on the interpretation of the recoil measurement or the relevance of different units of force. Multiple competing views remain regarding the context and implications of the recoil force.

Contextual Notes

There are limitations in the discussion regarding the assumptions made about the context of recoil, the definitions of units, and the mathematical steps involved in the calculations presented.

Ashkan
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when it is said that the recoil of a 120mm mortar is 40 tons, which one is meant to be the recoil: the reaction force exerted from gases on the recoil mass, OR the transmitted force from recoil system to the platform or vehicle (if it is mounted on a vehicle)?

Thanks...
 
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Both, depending on context. Also, a ton is not an SI unit of force.
 
Dickfore said:
Both, depending on context. Also, a ton is not an SI unit of force.

two words: conversion factors. :P
 
tkshoe said:
two words: conversion factors. :P

two and a half words: variation of g.
 
Dickfore said:
two and a half words: variation of g.

one word: negligible :)
 
tkshoe said:
one word: negligible :)

How about on an inclined plane at [itex]\alpha = 60^{\circ}[/itex]?
 
Dickfore said:
How about on an inclined plane at [itex]\alpha = 60^{\circ}[/itex]?

Ok... I thought you were referring to g as gravity, and therefore variation in g would be negligible since this is not a super duper mortar. But now that you have mentioned an angle... I have no idea what you are talking about. Mind clarifying what you were referring to as "g"?

Regardless, a ton is 2000 lbs and lbs easily convert to Newtons which I assume are your desired "SI" units. Hence my, albeit somewhat snide, comment about conversion factors.
 
What is a pound a unit of?
 
recoil is 80,000 pounds force exerted on the mortar's base plate...
 
  • #10
Dickfore said:
What is a pound a unit of?

pound is a unit of force as are tons as are Newtons with Newtons being the SI unit of force. I am done now, this is going nowhere.
 
  • #11
tkshoe said:
pound is a unit of force as are tons as are Newtons with Newtons being the SI unit of force. I am done now, this is going nowhere.

Why is the amount of groceries measured in units of force?
 
  • #12

1000Kg = 1 tonne. Is a unit of mass, not force. (1pound=0.45kg)

http://en.wikipedia.org/wiki/Kilogram"

For force: 1Kgf = 1g N = 9.81 N (10N). g = gravitational acceleration (constant)

http://en.wikipedia.org/wiki/Newton_(unit)"

From momentum conservation law.
m1V1=m2V2
m1,V1-projectile mass and speed; m2,V2- mortar mass and speed
And can calculate the force that generated the movement.
40tf (40.000 Kgf) = 400KN (400,000 N)
 
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