# Weight of a plane

A large passenger jet is standing on a runway. You have a toolbox, filled with some typical tools -- perhaps one that could be used to repair a bike or a car or something. How do you find the weight of the plane?

Related General Discussion News on Phys.org
I'll look it up. (Meaning I'll find the mass from the handbook.) :tongue2:

My personal favourites (though apparently not correct, who knows why ):

- Throw a spanner past the plane and measure the deviation due to gravitational attraction
- Throw the whole toolbox at the plane hard enough for it to go through and lodge in the plane somewhere, and measure the recoil of the plane.

You know, if the toolbox has a torch, we could shine light from behind the plane and measure the deviation of flash light. (Hmm...I wonder if it's Flash light or Flash-light...).

Or the acceleration due to photon pressure... People never seem to believe me when I say my eyesight and sense of timing is that good. So cynical...

arildno
Homework Helper
Gold Member
Dearly Missed
In my typic toolbox, I always carry with me the technical specification sheet for the plane I'm about to board.

I'd check that one out first.

I heard this one before. First you weigh the plane with the toolbox on board, then you weigh the toolbox. The weight of the plane is the difference.

Err, couldnt you just weight the airplane w/o the tool box? What would be the point of taking the difference?

Err, couldnt you just weight the airplane w/o the tool box? What would be the point of taking the difference?
What's that...? Sounds like a plane flying overhead...

I'll find the force on the Earth due to the plane.

I suspect someone will read all the posts in this thread and make up a story (and eventually electronic spam) about how a famous scientist, when he was young (I'm sure it will be a 'he'), gave all these answers for the question "How do you weigh a flying plane with a toolbox?" and was failed in the exam just because he didn't give the "correct" answer.

Hey, I've posted approximately $1000\sqrt{3}$ posts! And 3 non-GD posts ago I would have had a Ramanujan Number of posts.

Last edited:
What if this airplane were on a conveyor belt on takeoff?

What if this airplane were on a conveyor belt on takeoff?
:rofl: It wouldn't take off! :tongue:

Noooooooooooooooooooooooooooooooooooooooooo.

Edited: I forgot about the invisible color thingie...

I would try to estimate it based on the tire pressure and the contact area of all tires...

Last edited:
How long should I wait before writing down the "correct" answer?

How long should I wait before writing down the "correct" answer?
I'm afraid it's already too late. I posted it myself. If you have an incorrect answer you would like to post, do so at your convenience.

I think the first step would be measuring the pressure of the tires...

measure the wingspan, find out how much the wings can lift at different speeds. Jump in the plane and start going down the runway until it takes off. Take into account wind speed.

First off you will need to search the airport and check if they have a scale. If not you will have to build a scale, it should not be too hard as there are many useful items in the plane such as springs which could be used to construct a way of measuring mass. You will also need to find something of known mass.

I don't know about you guys but I ussually carry dynamite in my toolbox, but there is probably something at the airport which you could use as to construct explosive(fertilizer and jet fuel?) with enough time to do so.

Place the plane in the hangar, hopefully the hangar is has pretty strong walls. Now just plant enough explosive in the plane to fragment it into small pieces. Does not have to do a perfect job, some cutting can be done. Collect the ash and put it into garbage bags and measure the mass of each garbage bag. Then use a tool to cut the rest of the plane into smaller pieces if necessary and again gather the pieces into garbage bags and measure their mass. Add up the masses to get a fairly good approximation of the mass of the plane.

No one said you couldn't recruit a 100 man team to help.

(Yes I admit that my solution is not very plausible.) ;)

Last edited:
I think the first step would be measuring the pressure of the tires...

Nice hint. Then measure the footprint of the tires on the runway...

It's not totally accurate but it works.

A large passenger jet is standing on a runway. You have a toolbox, filled with some typical tools -- perhaps one that could be used to repair a bike or a car or something. How do you find the weight of the plane?
Pose as a airplane mechanic and ask one of the other ground crew what it weighed in at.

Put it on a scale, obviously.

For an automobile, just open the drivers side door. For an aircraft, use your tools to open the inspection panel for the manufacturer's name plate and look for GVW (gross vehicle weight)

Pilot should have the required weight and balance sheet. Ask. How much precision required?