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Moments M2 Maths

-Crane is lifting a uniform beam (crane attached just to the right of the centre of the beam)
-Mass of 800 N at one end of the beam
-weight of beam =4200N
-length of beam =12m

Find the distance between the mass and the cranes vertical chain.
Beam is at rest. Please help if you can.
(edited 6 years ago)
Reply 1
Avatar for Pangol
Pangol
15
Original post by Dexter212
-Crane is lifting a uniform beam (crane attached just to the right of the beam)
-Mass of 800 N at one end of the beam
-weight of beam =4200N
-length of beam =12m

Find the distance between the mass and the cranes vertical chain.
Beam is at rest. Please help if you can.


I don't quite get what you mean. Is the mass at the left hand end of the beam, with the crane attached at the right? What do you mean "just to the right of the beam" - it must be attached to the beam somewhere! Do you mean just to the right of the centre of the beam? Is there a picture you can show us?
Reply 2
Avatar for Raffacak3s
Raffacak3s
OP
15
Original post by Pangol
I don't quite get what you mean. Is the mass at the left hand end of the beam, with the crane attached at the right? What do you mean "just to the right of the beam" - it must be attached to the beam somewhere! Do you mean just to the right of the centre of the beam? Is there a picture you can show us?


yh i meant the crane was attached just to the right of the centre of the beam sorry,
the mass is at the very end of the right hand side.
I suspect it's this:

Untitled.jpg
Reply 4
Avatar for Pangol
Pangol
15
Original post by Dexter212
yh i meant the crane was attached just to the right of the centre of the beam sorry,
the mass is at the very end of the right hand side.


Ah - clearer!

You need to give a name to the unknown distance. It doesn't matter where you use as a reference point, but it's probably easiest to do it from the right hand side, since you want to know the distance from the mass to the crane. Now take moments about a carefully chosen point, and use the principal of moments.
Reply 5
Avatar for Raffacak3s
Raffacak3s
OP
15
Original post by ghostwalker
I suspect it's this:

Untitled.jpg


Thats the picture wow
Reply 6
Avatar for Raffacak3s
Raffacak3s
OP
15
Original post by Pangol
Ah - clearer!

You need to give a name to the unknown distance. It doesn't matter where you use as a reference point, but it's probably easiest to do it from the right hand side, since you want to know the distance from the mass to the crane. Now take moments about a carefully chosen point, and use the principal of moments.


i still cant find the distance
Reply 7
Avatar for Pangol
Pangol
15
Original post by Dexter212
i still cant find the distance


Call the distance from where the chain is attached to the beam to the right hand end d.Try taking moments about the point where the chain is attached to the beam. The only tricky part should be finding the distance from this point to the centre of mass of the beam in terms of d. Then use the principal of moments. You should only have two moments to consider, so it won't be a massive equation.
Reply 8
Avatar for Raffacak3s
Raffacak3s
OP
15
Original post by Pangol
Call the distance from where the chain is attached to the beam to the right hand end d.Try taking moments about the point where the chain is attached to the beam. The only tricky part should be finding the distance from this point to the centre of mass of the beam in terms of d. Then use the principal of moments. You should only have two moments to consider, so it won't be a massive equation.


Thank you, ive done it.

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