Questions tagged [inertia]

Inertia is the tendency of a body to oppose changes to its state of motion. DO NOT USE THIS TAG for moment-of-inertia!

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Inertia on a rotating disc?

If I toss a ball upwards in a train moving with uniform velocity, the ball will land right back in my hand. This is because the ball has inertia and it continues to move forward at the speed of train ...
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2answers
119 views

Gravity vs Electricity see-saw analogy and speed of light

Does electricity exhibit anything like the following steps: 1) A ball is rolled down from left side of a very long teeter-totter or see-saw 2) The see-saw rapidly (immediately) tilts once the ball ...
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113 views

Inertia as a fundamental interaction

Why is Inertia not included as one of the fundamental interactions, yet gravity is included as one of the four known interactions, and there is an equivalence established between gravity and inertia.
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1answer
155 views

Is Newton's third law due to inertia?

Newton's third law states that each force has an equal and opposite force. If I kicked a ball, it would apply the same force on me. Is this due to the ball's inertia? To clarify, is the ball exerting ...
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1answer
54 views

Inertia over an airplane [duplicate]

When an airplane is traveling, it moves at the same speed as the earth does due to inertia, but since, the plane is not directly touching the globe, how does is the speed of the earth is associated ...
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1answer
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What happens when a electrically charged object is moving away from a charge it is attracted to(read description) [closed]

When a electrically charged object that carries momentum and inertia is attracted to a electrical field and is moving away from it, does it lose momentum as it is pulled towards it, or does it circle ...
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1answer
68 views

How to stop the propagation of waves?

I am trying to understand Newtonian equivalent law of inertia for the waves. Roughly Newton's law of inertia says that an object which is in motion in space will continue to remain in motion unless an ...
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2answers
478 views

Is a heavier baseball bat better than a lighter one?

Baseball season is coming up and I would like to know which bat is best for me. I think the heaviest bat I can swing good would be the best, but my brother thinks the lightest bat would be the best so ...
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137 views

Will anyone please explain this problem using 4 fundamental forces?

If there are only four fundamental forces (gravity,e.m.,strong,weak) in the universe and all other forces can be expressed as a function of them then consider this problem. Suppose I throw a particle '...
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2answers
157 views

Inertial force in a bus [duplicate]

While i am standing in a bus that is accelerating an inertial force is acting on me in the direction opposite of acceleration (I understand that). But, what is the magnitude of that force.I thought it ...
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0answers
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Can I model objects as point masses when calculating rotational inertia? [duplicate]

I have an aircraft. On it are weapons. Weapons have masses and centers of masses. The larger aircraft system has a center of mass. I wish to calculate the cumulative rotational inertia of only the ...
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1answer
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Sciama's paper, On the origin of inertia

In his paper "On the origin of inertia", Sciama identifies $\frac{\Phi + \phi}{c^2} = -\frac{1}{G}$ This identity has confused me because I wonder how the right hand side arises since $\frac{\phi}{c^...
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Is the inertia of light equal to the inertia of mass under $E=mc^2$?

Under $E=mc^2$, 1kg of matter has $9\times 10^{10}$ joules of energy. So, if I had just the light shining from $9\times 10^8 $ 100 Watt light bulbs inside a perfectly reflective box, would that light ...
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4answers
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What is the relationship between gravity and inertia?

What is the relationship between Gravity and Inertia? Einstein told us that gravity and inertia are identical. And from the fact that two different masses fall at the same rate, I believe we can say ...
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5answers
174 views

Is it possible to measure inertial mass without gravity or rolling?

Is there a reliable (and ideally, easy to construct+tune) method of measuring inertial mass without using gravity (e.g. weighing on a scale or a freefall apparatus or a pendulum) or rolling (e.g. ...
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0answers
20 views

Will variable but symmetrical density spheres which are otherwise identical swing at the same rate?

If you have a pendulum with the same length and different spheres on the end will the period be the same if the only variation is the distribution of mass from the center of the sphere? This is to ...
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4answers
871 views

Why do gravitational mass and inertial mass appear to be indistinguishable? [duplicate]

I have learnt that heavier the object is (the more gravitational mass it has), the more resistance to the change of motion it is (the more inertial mass it has). I can accept this fact but I can't ...
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2answers
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Does Inertia “conflict” Entropy?

Earth continues to spin because of inertia. Does this fact "conflict" the entropy of the universe? Since the tendence is towards disorder, how is Inertia of planets Spin related to Entropy?
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What determines the amount of inertia of matter?

what factors would increase or decrease inertia, i.e. require more or less energy to change the velocity of matter from what is currently required all else being equal? I have heard of mach's ...
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1answer
125 views

What is the universal definition of 'inertia' in fields?

In my physics class we recently did the Gravitational Field unit, and the idea of gravitational field strength was introduced: $$g=\frac{F}{m}=\frac{GMm}{r^2}\frac{1}{m}=\frac{GM}{r^2}$$ After doing ...
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2answers
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Understanding the meaning of mass in Newtonian mechanics

So, I was reading a book on mechanics and there I found the following notion about mass. It says that "Experience shows that every body resists any effort to change its velocity,both in magnitude and ...
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2answers
102 views

How does Newtonian gravity violate law of inertia?

I came across a line on http://physics.ucr.edu/~wudka/Physics7/Notes_www/node49.html " If the experiment is tried in vacuum any two objects when released from a given height, will reach the ground ...
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2answers
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Clarification regarding accelerating Car with packed environment

the question is when the car accelerates the atmosphere inside that packed car also accelerates due to the inertia but in a car (with height more than 10 feet) in which superman is in no contact with ...
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1answer
250 views

What causes inertia? [duplicate]

Inertia forms the basis of Newtonian physics,but nothing really explains it.I know that it is generally accepted in classical physics,but can it's origin be explained?Maybe be relativity or quantum ...
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3answers
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Would a spinning object like a fan stop faster in a non-gravity environment?

Let's say there is a fan spinning and stops in exactly 1 minute on earth. Would it stop faster or slower or exactly same time in a spacecraft without gravity but exact same density of air. Btw: let's ...
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1answer
81 views

Sensing fictitious forces

I need to clarify my understanding of fictitious forces and our sensation of them. It is my understanding that fictitious forces are terms added when Newton's laws are resolved in accelerating ...
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1answer
53 views

How should one determine the motion of extremely large extended objects?

[To put this question in context, I was reading "How much time will it take to move an object whose length is equal to one light year?" and don't really feel satisfied by the answer that has been ...
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1answer
77 views

Calculating New Velocity Vector of Moving Object [closed]

A 1kg object is moving through space. A force is applied to the object of 1N perpendicular to the direction of travel for 1 second. Assuming there are no other external forces on this object, (...
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2answers
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Split moments of inertia into vectors - Right thing to do?

Let's say that we have the moment of intertia: $$J = mR^2$$ And the mass $m$ is on the $(x, y)$ position. Can I say that moment of intertia is then: $$J = mR^2 = m\sqrt{x^2 + y^2} ^2 = m(x^2 + y^2)$...
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4answers
273 views

What units is the moment of inertia for a point mass?

What are the units used in the integral equation for the point mass moment of inertia. Specifically what are the units of the double integral over a region R of $r^2· \rho· dA$, where $r$ stands for ...
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3answers
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Why does a bowling ball roll down faster on a slope than a tennis ball, yet both hits the ground at the same time if they're dropped from the rooftop? [closed]

If a tennis ball and a bowling ball are dropped of a rooftop, they hit the ground at the same time. But if they are rolled down a slope, the bowling ball rolls faster. Why?
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How would I move if I grew by a factor of 3 in each physical dimension?

Suppose, for the sake of this thought experiment, I am structurally identical to an average human, with the only difference being that my body is scaled in all directions by factor of 3. This would ...
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1answer
140 views

Does free-fall imply that it is impossible to quantize gravity? [closed]

I will start by stating that I realise that there already exist questions on the compatibility of GR and QM (e.g. here) but my question is different. In this essay the following argument is made (pg ...
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2answers
225 views

What causes a particular object to have a tendency to go outwards in circular motion when the centripetal force is inwards to the center [duplicate]

Like a circular bead with a thread passing through it and the system being rotated . It can't be centrifugal force as it is pseudo only and has no existence when we are already in an inertial frame ...
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1answer
189 views

A Conceptual (philosophical) doubt on equivalence principle

The reference is: Elements of Newtonian Mechanics by J.M. Knudsen; Springer; page 108 to 113. My doubt is about the significance of the apparent distinction between Gravitation and Inertia. In ...
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Question on Inertia [closed]

I'm trying to get the concept right. If an object is accelerating in a straight line, with no opposing forces acting on it, will it continue to accelerate forever due to its inertia?
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0answers
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Avoiding inertial affects by accelerating larger mass in 2 body system

Suppose two bodies S and L are in proximity (asteroids say). L is substantially larger than S. For simplicity, let them initially have negligible angular and linear velocity. S will begin to fall ...
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2answers
417 views

How did Newton prove the equivalence principle with pendulums?

I know pendulums may be equivalent to a free fall but I would appreciate any further explanation for it.
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1answer
494 views

Why doesn't a test charge placed in an electric field, trace out the same path as the electric field lines?

Consider for example a positive charge placed between a positive charge and a negative charge. Initially the test charge is placed closer to positive charge. Why is path followed by the test charge ...
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1answer
73 views

Is the inertia of a mass depended of his speed?

If a ball (10 kg) falls from a height of 10 km towards an (air free) planet with an acceleration of 10 m/s² then it gains every second in speed. But is the inertia of the ball getting every second a ...
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2answers
200 views

Does horizontal inertia affect the time it takes something to reach the ground?

I am quite new to physics. I have just started learning vectors after learning the kinematic equations and Newton's Laws of Motion. One thing that blew my mind was being told that a bullet or a ball ...
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1answer
74 views

Global momentum of a closed universe [closed]

In a universe: with 2 spatial dimensions closed (that loop on itself) with local positive and negative curvature with no attraction and no repulsion with particles randomly created by pair in the ...
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3answers
636 views

Does orientation matter when calculating inertia?

Two cylinders having the same mass, radius, size, shape and angular property are both rotating. Does this two identical cylinders have the same inertia despite their orientation?
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1answer
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Using a gyroscope to get to space

Theoretically, if you could get an inertial mass or gyroscope spinning fast enough while on the earth' s surface, then as the earth turned would it continue to travel in a straight line and therefore ...
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2answers
98 views

What stops a projectile from going forward endlessly?

What stops a projectile from endlessly flying forward? Excluding gravity since it's an obvious one. Wind resistance is something that would eventually stop the projectile, anything else? Other that ...
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2answers
394 views

Ball inside an accelerating frame

Why does a ball inside a moving bus at rest start moving backwards when the bus suddenly accelerates? Also does the moving ball have some acceleration? This is my theory: Initially the bus and the ...
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2answers
952 views

Why are mass and the moment of inertia additive?

I have previously wondered about why mass is additive; i.e. the translational kinematics of some bodies can be determined by considering them as a single body with a total mass equal to the sum of the ...
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3answers
525 views

Does the Earth keep spinning because of inertia?

I understand that the earth continues to rotate about its axis because the angular momentum is conserved. (Am i wrong?!) But, I have seen quite a few sources cite that inertia is the reason why the ...
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0answers
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Does it make sense an inertial mass dipole moment for massless particles?

Electric and magnetic dipoles exist in nature even with zero net electric and magnetic charge Electrons have a unit of charge, about $10^{-31}$ kg of inertial mass, zero electric dipole moment, $\...
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4answers
606 views

Does law of inertia has anything to do with speed of light?

I am not physics student so please pardon me if this sounds silly because I might be mixing irrelevant things here and I am not even getting how to ask my question. My main question is, does light ...