Is a Moment the same as Torque and is it just about Levers?

A friend of mine just asked the following question after hearing Richard Hammond make a comment. She said:

“I think Hammond got it totally wrong when he gave a metaphor for a dragster suddenly swerving and crashing (a ‘moment’) as the difference between using a short-handled, smaller spanner to using a longer-handled, bigger spanner to tighten a bolt (no – in my book, the spanners show a difference in ‘leverage’). It is always recommended that women (yeah, yeah – depending on size and body-building, etc.) use longer-handled spanners, etc., because they give more leverage. Am I wrong, or missing something? Leverage, in my book, has nothing to do with “moments.” Come on e-learning teacher!”

And my reply is as follows (they are both correct by the way, but using different words for the same thing!):

A longer lever (spanner) means you need less force on the end of it to produce the same torque (turning force) at the nut – a person with a shorter spanner would need to apply more force on the spanner than you. This is as you suggest, the law of levers. Torque is arguably the same thing as a Moment which is defined as: “A turning effect produced by a force acting at a distance on an object.” Or perhaps better as: “The magnitude of a turning effect produced by a force acting at a distance, expressed as the product of the force and the distance from its line of action to a given point.”

Force (N) x distance (m) = Torque (Nm or Newton-meters)

However, moments are usually used to describe the way combinations of forces affect something. As long as all the moments on a car cancel each other out for example then it will not start to spin!

If you have a moment to spare – please add a comment! 🙂


PS. Why are we all so worried about Clark’s son at the moment – and who is Clark anyway?

PPS. To all my good friends in the USA a spanner is the proper name for a wrench…

2 thoughts on “Is a Moment the same as Torque and is it just about Levers?”

  1. Hi Tom!
    Great post explaning the terms “moment” and “torque”. As far as automotive terms are concerned, “damper” is technically correct as opposed to “shock absorber” which is what I’ve always called it, along with my American counterparts. However, I think you need to replace the word “boot” with “trunk”. I can’t imagine putting my tools and other stuff into something I wear on my feet, LOL! Always a good time comparing British and American automotive terms. Keep up the good work on your excellent website!

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