January 26th, 2015, 08:09 AM  #1 
Math Team Joined: Jul 2013 From: काठमाडौं, नेपाल Posts: 878 Thanks: 60 Math Focus: सामान्य गणित  pushing pulling
why is pulling easier than pushing ?

January 26th, 2015, 08:13 AM  #2 
Math Team Joined: Dec 2013 From: Colombia Posts: 7,331 Thanks: 2457 Math Focus: Mainly analysis and algebra 
I think that when we pull their is a tendency to lift at the same time which reduces the frictional force. Conversely, pushing tends to impart a downward force which increases friction.

January 26th, 2015, 08:17 AM  #3 
Math Team Joined: Jul 2013 From: काठमाडौं, नेपाल Posts: 878 Thanks: 60 Math Focus: सामान्य गणित 
could you please involve some vectors to show the components of the applied force ?

January 26th, 2015, 08:22 AM  #4 
Global Moderator Joined: Nov 2006 From: UTC 5 Posts: 16,046 Thanks: 938 Math Focus: Number theory, computational mathematics, combinatorics, FOM, symbolic logic, TCS, algorithms 
From a purely mechanical point of view, F = ma and they are the same. But depending on the task one or the other might be easier. If the surface is rough, friction is high and pulling will tend to lift the object up, reducing friction (at the cost of less force remaining to go forward, but that might be worthwhile). If the object is heavy and the surface smooth you might have more biomechanical efficiency pushing because you can brace against the object. Apparently you find yourself more in the first case than the second.

January 26th, 2015, 08:29 AM  #5 
Senior Member Joined: Apr 2014 From: Glasgow Posts: 2,119 Thanks: 710 Math Focus: Physics, mathematical modelling, numerical and computational solutions 
You can also lean backwards, letting the torque from your body's rotation convert to linear motion for a short time. You're basically letting gravity do some of the work for you, although you have to correct your position every time you rotate. You can do this with pushing too, but it's more awkward and you might fall on your face . 
January 26th, 2015, 08:32 AM  #6 
Math Team Joined: Jul 2013 From: काठमाडौं, नेपाल Posts: 878 Thanks: 60 Math Focus: सामान्य गणित 
what if we pull or push horizontally ?

January 26th, 2015, 10:16 AM  #7 
Global Moderator Joined: Nov 2006 From: UTC 5 Posts: 16,046 Thanks: 938 Math Focus: Number theory, computational mathematics, combinatorics, FOM, symbolic logic, TCS, algorithms  That's what I'm talking about. If the center of gravity of the thing you're pulling is below your shoulder you're pulling it upward as well as horizontally. If it's at exactly shoulder level then there's no lifting advantage (or disadvantage) vs. pushing.

January 26th, 2015, 11:55 PM  #8 
Math Team Joined: Jul 2011 From: North America, 42nd parallel Posts: 3,372 Thanks: 233 
I don't think pulling exists , its all pushing in different forms. 
January 27th, 2015, 05:46 AM  #9  
Math Team Joined: Jul 2013 From: काठमाडौं, नेपाल Posts: 878 Thanks: 60 Math Focus: सामान्य गणित  Quote:
and if its above shoulder the effect is just reverse ?  
January 27th, 2015, 05:54 AM  #10 
Global Moderator Joined: Nov 2006 From: UTC 5 Posts: 16,046 Thanks: 938 Math Focus: Number theory, computational mathematics, combinatorics, FOM, symbolic logic, TCS, algorithms  Yes. So if your shoulder is 5 feet off the ground and you're pulling a uniformly dense prism (parallel to the ground), then if it's less than 10 feet tall you're lifting it off the ground slightly, and if it's more than 10 feet tall then you're pulling it into the ground slightly.


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