My Math Forum  

Go Back   My Math Forum > Science Forums > Physics

Physics Physics Forum

LinkBack Thread Tools Display Modes
December 9th, 2018, 03:59 PM   #1
Joined: Aug 2018
From: Nigeria

Posts: 73
Thanks: 2

Help me on equilibrium

Anyone help me!!! How do I solve this, members explain to me, please, and do I need diagram for this? Help. I'm a nonentity, I need a step by step explanation. I don't even know whether it is rotational or translational. Help me, please.

A uniform horizontal beam AB of mass 30kg and length 2m rest on a fulcrum at F distance 102cm from A. Masses of 2kg, 3kg, 4kg and 5kg are hung at C, D, G and H, which are 24cm, 60cm, 120cm and ycm from A respectively. Find the value of y.
2. The reaction R at point E

Last edited by skipjack; December 11th, 2018 at 03:13 PM.
Harmeed is offline  
December 9th, 2018, 08:50 PM   #2
Global Moderator
Joined: Dec 2006

Posts: 20,644
Thanks: 2084

I've provided a diagram, but you'll realize that it isn't needed. I'll assume that gravity is acting downwards (i.e. the curvature of the earth is to be ignored).

As the beam "rests on a fulcrum", I'll also assume the beam is in equilibrium.

I can now write the (simplified) equation below, in which each term represents a moment (about the fulcrum), which is force (due to gravity) times (horizontal) distance from the fulcrum. I've omitted all units and g (the acceleration due to gravity), as they're the same for each term.

2(102 - 24) + 3(102 - 60) + 30(102 - 100) = 4(120 - 102) + 5(y - 102)

That simplifies to 342 = 5y - 438, so y = 780/5 = 156.

As the beam is uniform, its mass is treated as though it's entirely at a point halfway along the beam.

Is the question about R mistyped? There's no information in the question about point E.
skipjack is offline  

  My Math Forum > Science Forums > Physics


Thread Tools
Display Modes

Similar Threads
Thread Thread Starter Forum Replies Last Post
Equilibrium prashantakerkar Physics 2 March 20th, 2017 02:26 AM
Equilibrium Or so I think ItsCathingMe Physics 2 April 21st, 2014 02:16 AM
Equilibrium Evil Tomato Physics 2 December 8th, 2010 01:35 PM
Equilibrium Francesco Mureddu Economics 4 September 27th, 2010 02:49 PM
Equilibrium Francesco Mureddu Calculus 1 August 24th, 2010 05:09 PM

Copyright © 2019 My Math Forum. All rights reserved.