# 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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### Relation between force and torque for a set of gears/bicycle

If there are 2 gears meshed together and they are of different sizes, then rotating the smaller one will make the larger one spin with a smaller angular velocity but with more torque. And the opposite ...
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### Boundary behaviour of a mechanical wave

Let us assume we have a taut rope and I introduce a pulse in it by whipping one end. Now if instead of a clamp, I have tied the other end of the rope to a denser rope, a part of the energy is ...
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### An intuitive explanation regarding propagation of mechanical waves

I was studying mechanical waves today and have questions regarding how a pulse is propagated on a string and its reflection and transmission at a boundary and I hope I can find help here. First, ...
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### How does a cyclist moves the center of mass of the cycle-cyclist system?

Consider the image shown below, In the left diagram the centre of mass of the system lies upon the perpendicular from the point of contact. But in the right diagram the centre of mass has shifted ...
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### What is the difference when we measure torque/angular momentum about a point and about an axis?

When do we measure torque about an axis and when do we measure torque about a point?Whats the difference? I tried searching this on google but did not get satisfactory answer.
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### Why do linear momentum and angular momentum have to be conserved in ground frame only?

According the Newton's second law of translational and rotational motion respectively if the net external force /torque acting on a body is zero then the linear/angluar momentum is a constant . So ...
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### If a bullet were to hit a target point blank, would the force upon impact be the same force as the recoil?

When a bullet fires from a gun the force exerted on the bullet by the blast is equal and opposite to what you feel as the recoil. I know that acceleration on both the gun and bullet is different due ...
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### Rotation of a cube around its diagonal axis

I have the following multiple choice question that I am attempting to answer: For B1.3, (a) appears to be the most logical choice. It is my understanding that an object whose shape is asymmetric ...
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### Angular momentum about a moving axis

How can we define angular momentum of a system about an axis that moves parallel to itself? For example Axis passing through CM that is perpendicular to plane of body. When we talk about ...
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### What is required for a time-varying moment of inertia matrix?

Let me preface this question by stating that I am familiar with euler's equations for rigid body dynamics, torque and angular momentum. Despite the math, I'm still a little fuzzy about certain ...
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### What happens if a motorcycle going at 50mph crashes head into a car going at 60mph? [closed]

I wonder if a motorcycle (going at 50mph) crashes into a car (going 60mph), what is the damage that motorcycle will experience? Here's a diagram that shows what I've in mind: ...
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### How to show that the configuration space of two beads on a rod is a triangle?

I do math, and this problem showed up in the setting of translation surfaces. Lets say we have two beads of masses $m_1$ and $m_2$ on a rod of length $a$, with $m_1$ on the left of $m_2$. Denote ...
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### circular motion relative velocity question

You are standing in the middle of a disk of radius $2\:\mathrm{m}$ rotating at $\pi\:\mathrm{rad s^{-1}}$, and there's a smooth puck at $1.5\:\mathrm{m}$ away from the centre. If the puck was released,...
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### If, for a body rolling on an incline, the friction coefficient isn't enough to allow pure rolling will it still roll?

More specifically that it won't be pure rolling (obviously) but would it still have some rotational motion along with its translational motion? (if yes how would we write their mechanical equations). ...
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### how to reduce the order of the hamiltonian equation for electrical problem given below?

I am having my FYP in this Hamiltonian project to analysis the integrator for Hamiltonian system. Can anyone please guide me how to reduce the equations to first order using substitution method?
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### Why is it easier to pull a lawn roller rather than pushing it?

Does it have something to do with friction or weight distribution in pulling is favorable or anything else ?
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### How do forces affect work? [closed]

I was doing my homework and I came across the question: Suppose that two objects, each with the same mass, are accelerated from rest to the same velocity. The force that accelerates one object ...
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### How is this seemingly counterintuitive result in a rotation problem explained?

In the classic spool problem, where a spool of string of mass M is unrolled with a force F, like in the diagram, after working through the equations with Newton's laws of rotation and translation, we ...
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### Magnitude of tension in a bent string

I understand tension in a straight string as a reaction force to a weight, which acts along the string, ultimately resulting from the attractive forces between the constituent particles of the string. ...
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### Are some laws in physics really as simple as they seem?

For example, is $F = ma$ really an exact formula, or is it an approximation? I know a lot of formula's come from taking the first few terms of a Taylor expansion, so I was wondering if the simple ...
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### Tension in string question [closed]

Problem: A 12.0-kg box resting on a horizontal, frictionless surface is attached to a 5.00-kg weight by a thin, light wire that passes without slippage over a frictionless pulley (the figure (Figure 1)...
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### string applying a force on pulley

Why should string apply a force on pulley?(like atwood machine cases)and does that mean the pulley will exert an equal force on string(newton's third law)? Please explain in detail,if possible ...
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Take the case of Atwood machine where masses of blocks are $m$ and $2m$. The acceleration of individual masses are $\frac g3$. now the acceleration of center of mass of masses and string system is ...
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### Does an object decelerate when reaching terminal velocity

I'll take the sky diver example. Right when a sky diver jumps out of the plane the net force of the diver is greatest. Then the diver begins to reach terminal velocity where the force of resistance = ...
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### Time spent in eclipse of an object

Well consider an orbit - I'm trying to calculate the exact time spent in the shadow of the body you orbit around. An explanation of "shadow" (sun is positioned to the far left): For a circular ...
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### Why do objects move when you apply a force that's equal in magnitude to the friction? [duplicate]

If the friction on an object is 200 N and you apply 200 N, it seems, the forces should immediately cancel each other out since the friction and your applied force go in opposite directions, leaving ...
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### Why is friction not dissipative in rolling motion? [duplicate]

We know that non-conservative forces like friction is a dissipative force. But according to my book when a solid cylinder is rolling down a rough inclined plane of inclination angle $\theta$ the ...
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### What is the distance between two objects in space as a function of time, considering only the force of gravity? [duplicate]

What is the distance between two objects in space as a function of time, considering only the force of gravity? To be specific, there are no other objects to be considered and the objects in question ...
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### Why does Goldstein's derivation of orbits from Newton's law not yield the orbit consisting of symmetric oscillation along a line thru center of Sun?

Why does Goldstein's derivation of Keplerian orbits from Newton's law of gravity not yield the orbit consisting of symmetric oscillation along a line passing thru the center of the Sun? The fact that ...
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### Pushing down on the gas pedal of a car a good example of jerk?

I'm trying to think of the clearest examples to demonstrate the concept of jerk to a layman. Ignoring drag and making other reasonable assumptions (friction is conveniently there to only allow you to ...
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### Conservation of momentum in inelastic conservation

Why does momentum and velocity change along contact normal but not contact tangent In in elastic collision? Suppose a ball strike an inelastic surface. It's velocity component does not change along ...
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### Roller Coaster Physics

I am trying to figure out how to calculate the $g$-forces throughout a non-uniform corkscrew as well as the exiting velocity. Do you calculate each radius separately and each $g$-force separately ...
I recently came across the definition of gravitational potential where ..... Suppose a particle of mass $m$ is taken from a point $A$ to $B$. Let $U(A)$ and $U(B)$ denote the gravitational ...
I know that $F = mg$ so $2,00 \textrm{ KG m} \cdot 9,81 \textrm{ N g} = 19,62 \textrm{ N F}$ Why does my book say that the weight of a $2,00 \textrm{ KG}$ object is $19,62\textrm{ N}$, the mass is \$2,...