# Tagged Questions

Newtonian mechanics covers the discussion of the movement of classical bodies under the influence of forces by making use of Newton’s three laws. For more general discussion of energy, momentum conservation etc., use classical-mechanics, for Newton’s description of gravity, use newtonian-gravity.

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### Does friction depend on the direction of motion?

In my experiment of finding the moment of inertia of a flywheel, I first rotate the flywheel in the anticlockwise direction and then in the clockwise direction, but I am getting different values of ...
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### Can we use the planets and Sun to fling out a craft at relativistic speeds? [duplicate]

E.g. The Voyager crafts took various assists from the planets. Sun being much more massive, wouldn't a spacecraft gain much more energy from such a flyby on the correct trajectory? If so then what ...
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### Impact on landing with forward motion vs straight down

A skateboarder ollies down a set of stair. Is the impact when landing less than if dropped straight down from the same height?
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### Why can't I push myself in a chair? [duplicate]

If I am sitting in a chair with wheels and someone pushes on the back of my chair with sufficient force it will role along the ground. However, if I push on the back of the chair with the same force ...
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### Force exerted on carseats?

Can anyone explain how force is exerted on car seats during a crash? I am being told in car seat safety forums that $force=mass \times acceleration$. So if a $2000 \;\text{lb}$ vehicle bumps you at ...
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### What is the proper vector form for the Gravity Formula?

We are familiar with the equation for calculating the velocity of an object in orbit given the central mass (or the mass given the orbital velocity): $$\frac{v^2}{r} = \frac{MG}{r^2}$$ I'm trying to ...
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### Are the effects of faraday's law of induction worth considering in this experiment?

In my intro to physics lab at uni, we did an experiment where we were supposed to measure the amount of kinetic energy and momentum before and after collisions between two carts. For some reason, ...
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### How to start an artificial gravity?

I understand how artificial gravity in space stations works. It is by normal force the wall exerts on the foot. But I wonder how to start it in the first place. I just learned about centrifugation ...
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### If there is a non-slipping string pulling a cylindrical object, is the rotational acceleration the same as the translational acceleration?

The rotational velocity and translational velocity are the same right? Assuming the cylindrical object does not interact with anything other than the string which applies a force.
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### Inertia of yo-yo goes to infinity, what is tension and acceleration?

For this part, imagine that the string is wound around the center axle of a yo-yo; the axle radius is Raxle, but the yo-yo casing has a radius Rcasing≫Raxle and moment of inertia I≫mr2axle. In the ...
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### From Newton to Kepler without infinitesimals

I've read some interesting calculus-free proofs of at least parts of the derivation of Kepler's Laws from Newton's gravitational force. One is of course Feyman's "Lost Lecture" (which was already ...
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### Phase space orbit for a projectile [closed]

After playing around with drawing the phase space orbit for a harmonic oscillator I started wondering about the case for a free falling object. So the equations of motion are: $$P = P_0 + mgt$$ ...
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### Confused about potential energy problem

So I am trying to solve this problem: On spring hangs a 2 kg block. Spring stiffness coefficient is 400 N/m. How much spring expanded? My attempt to solve it: ...