Newton's Laws - Pushing on a heavy object

In summary, if a person were to push against a mountain on Earth, the effect would be infinitesimally small due to the astronomical difference in mass between the person and the mountain. This is because the mountain is held in place by atomic and molecular forces. However, if the person and the mountain were both floating in space, pushing off each other would cause both objects to move apart. Additionally, when considering the most massive object on Earth, the Earth itself, even jumping would have an infinitesimally small effect on its position.
  • #1
Einstein
13
1
I'm trying to understand if a really heavy object on earth, say a mountain, would move if I push it with my bare hands. This sounds absurd but according to Newton's Laws, if I push against the mountain it will exert an equal and opposite force. I understand there are other forces like gravity and friction involved but does it mean that me pushing on it will effectively move the mountain and because of the astronomical difference in the mass between me and the mountain, the effect will be infinitesimally small? or is it that there will be absolutely zero displacement?
 
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  • #2
You will be pushing on the mountain, which will exert a force back on you, and all you will end up doing is moving a little bit of dirt around as you hands and feet slide around. Other than the dirt there will be no displacement because the mountain is part of the ground and is held there through atomic/molecular forces. If you were both floating in space and you pushed off the mountain then both you and the mountain would begin to move apart.
 
  • #3
Einstein said:
I'm trying to understand if a really heavy object on earth, say a mountain, would move if I push it with my bare hands. This sounds absurd but according to Newton's Laws, if I push against the mountain it will exert an equal and opposite force. I understand there are other forces like gravity and friction involved but does it mean that me pushing on it will effectively move the mountain and because of the astronomical difference in the mass between me and the mountain, the effect will be infinitesimally small? or is it that there will be absolutely zero displacement?

How about running this experiment on a really heavy object, in fact the most massive object on earth? That most massive object is... The Earth itself!

All you need to to do is to jump. Your feet are pushing on the earth, and the Earth is pushing back with an equal and opposite force. The force of the Earth pushing against your feet will throw you into the air (how high can you jump?). Meanwhile your feet pushing on the Earth will move it ever so slightly in the opposite direction. How slightly? Well for reasonable assumptions about your weight and strength, maybe 10-21 centimeters, which is well and thoroughly undetectable.

So to answer your question: not truly zero, but infinitesimally small.
 

What are Newton's Laws?

Newton's Laws are three fundamental principles of physics proposed by Sir Isaac Newton in the 17th century. They describe the relationship between the forces acting on an object and its motion.

What is the first law of motion?

The first law, also known as the law of inertia, states that an object at rest will remain at rest and an object in motion will remain in motion at a constant velocity unless acted upon by an external force.

What is the second law of motion?

The second law states that the acceleration of an object is directly proportional to the net force acting on it and inversely proportional to its mass. This can be written as F=ma, where F is the force, m is the mass, and a is the acceleration.

How does the second law apply to pushing on a heavy object?

The second law can be applied to pushing on a heavy object by understanding that the force needed to move the object is directly related to its mass. The heavier the object, the more force is required to move it at a certain acceleration.

What is the third law of motion?

The third law states that for every action, there is an equal and opposite reaction. This means that when an object exerts a force on another object, the second object will exert an equal force in the opposite direction.

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