How Does One Move?

Classical Mechanics Level 2

A man is standing on a frictionless surface and there is no air resistance. If he wants to move, which of Newton's laws would he be using? Also Try my Easy Mechanics Set Easy Mechanics

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Third law of motion Cannot say Second law of motion First law of motion

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Kandarp Singh by Kandarp Singh , 22, India

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7 solutions

Pranay Pratyush
Jun 28, 2014

This is ambigous question. The answer could hav also been 1st law. As the conservation of momentum (I mean Newtonian not quantum) can be completely derived from 1st law. And the perfect answer would be conservation of momentum .

21 Helpful 1 Interesting 1 Brilliant 0 Confused

I think the first law would do the trick.There must be a resistance for the man to move, in case he wants to move on his own.:

1.If he wants to move by walking---sorry there's no friction on surface.

2.If he wants to move through expelling air----Sorry,no resistance by the air.

Then there must be an external agency,an external push or effort to make him move.

I think that sums up my reasoning.

I am open to any opinions which can prove me wrong through valid arguments.

Junaid Reshi - 6 years, 11 months ago

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amazing crap i have just read, get the basics right, newtons first law is law of inertia v=0, acc(acceleration)= o unless some exteral force pushes it. in this case no other skater with his own momentum does it for him. therefore 1st law cannot be applied. The great N's second law does not hold water either , ill tell you why because dude in this case the body has to be moved with a greater force and it goes in the direction of the greater force , no greater force is applied to the skater

The great N's third law fits as he has to move against the surface applying his own mass and accelerate from the point of inertia , to get the force to move and the only way this can be done is to move against the ground surface ie his force f=ma (his wt *acc) now acts against the surface at the point of inertia and the force created has an equal and opposite reactionary force in the opposite direction against the skater and propells him forward. QED

samraj n - 6 years, 6 months ago

Yes, It must be the 1st law ...

John Lloyd Venancio - 6 years, 11 months ago

explain...... whu applying or use.... 3rd law of motion...

Pooja Anand - 6 years, 11 months ago

third law is wrong one because it states that Action has equal and opposite reaction

Rahul Sharma - 6 years, 11 months ago

Yup air I also agree with you because here no air resistance so I thing third low may not be aplicabal

kuldip bum - 6 years, 11 months ago

even i think that it would be the first law

Ben Tennyson - 6 years, 9 months ago

Yea it would be the 3rd law as even if he blows air from his mouth he'll move

Priyesh Sheth - 6 years, 11 months ago
Rajeev Sharma
Jun 25, 2014

man should throw something opposite to direction of desired motion.

9 Helpful 0 Interesting 0 Brilliant 0 Confused

A sneeze would do the trick amazingly ....aaaaaannnnnncheeee.....oops had caught cold on solving this cool question

ashutosh mahapatra - 6 years, 11 months ago

Neuton;s First Law Of Motion.

Maddy RokKz - 6 years, 11 months ago

Exactly ,something like even a shirt would do cause in return a little force will be generated and that is enough cause the surface is friction less.

Vaibhav Chaturvedi - 6 years, 11 months ago

how the third law of motion is correct explain please

vikash raaj - 6 years, 11 months ago
Kandarp Singh
Jun 23, 2014

III rd law every action has equal and opposite reaction.

3 Helpful 0 Interesting 0 Brilliant 0 Confused

3rd law sh'ld b apply

prem pal singh - 6 years, 11 months ago
John M.
Jul 3, 2014

Well, actually, it's "Cannot tell", not only because he can use all three laws provided, but because he could be using neither. First of all, the question doesn't specify the reference point for the man's motion. So, relatively to the sun, he's already moving.

But assuming the question intends the floor to be the reference point, then he can move via a quantum leap, or by being randomly teleported via a wormhole through spacetime to another location. Those are unlikely, however, possible.

Oh, and he could also simply slip through the floor by just standing there.

Cheers,

1 Helpful 0 Interesting 0 Brilliant 0 Confused

Or he could be already moving, as standing does not imply anything about motion on a frictionless surface. In that case, it would be the first law. The third law is obviously something like blowing air out his mouth, but then the second law would also apply, as it relates the acceleration he experiences to the force he feels.

All in all, the question is pretty poorly worded.

Jason Gross - 6 years, 6 months ago
Samraj N
Nov 28, 2014

amazing crap i have just read, get the basics right, newtons first law is law of inertia v=0, acc(acceleration)= o unless some exteral force pushes it. in this case no other skater with his own momentum does it for him. therefore 1st law cannot be applied. The great N's second law does not hold water either , ill tell you why because dude in this case the body has to be moved with a greater force and it goes in the direction of the greater force , no greater force is applied to the skater

The great N's third law fits as he has to move against the surface applying his own mass and accelerate from the point of inertia , to get the force to move and the only way this can be done is to move against the ground surface ie his force f=ma (his wt *acc) now acts against the surface at the point of inertia and the force created has an equal and opposite reactionary force in the opposite direction against the skater and propells him forward. QED

0 Helpful 0 Interesting 0 Brilliant 0 Confused
Nitin Das
Jul 10, 2014

EASY !!! to move out of the f.less surface he simply throw a coin or anything with force ,reaction force of which will cause motion in the body. As there is no opposing force .he will move out of the surface..

0 Helpful 0 Interesting 0 Brilliant 0 Confused

atfirst someone confused that as their is no friction,so what is the reaction force but its due to 3rd law whenever u put some force there is some reply to u,intrinsic property of force :)

0 Helpful 0 Interesting 0 Brilliant 0 Confused

third law.... How is this possible... Explain me

prashant singh - 6 years, 11 months ago

The options are incorrect as the only solution is to throw something and move backwards with an equal momentum - this would be the third law (The only law applicable on different bodies). Second law is incorrect as an option, despite being the fundamental law, as it applies to one body only.

Aslam Sufian - 6 years, 11 months ago

3 rd law. Using scatting and rod. He will push forword himself by this law.

Vinod Chhallany - 6 years, 10 months ago

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