# Questions tagged [newtonian-mechanics]

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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### Find work done by force along a path - is parameterization the only way?

$F = x^3y^4 \hat i + x^4y^3 \hat j$ from $(0,0)$ to $(1,1)$. I am given different paths. For example, "ﬁrst along x axis and then along the y axis" is one of the paths. Is this problem solvable ...
1answer
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### Does a fly get brought up to speed with a bus?

Consider a scenario where a bus is moving at a constant speed and a fly enters through a window,the fly is also flying at a constant speed. Since the bus is not in contact with the fly and neither is ...
3answers
453 views

### When can one write $a=v \cdot dv/dx$?

Referring to unidimensional motion, it is obvious that it doesn't always make sense to write the speed as a function of position. Seems to me that this is a necessary condition to derive formulas like:...
2answers
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### Conservative Force and $1/r^2$

Does the inverse square law have anything to do with conservative behavior of the central forces?
1answer
3k views

### Is it really possible to walk on water? [closed]

Is it really possible to walk on water or levitate in air. If not then how do some magician,s like dynemo do it simply while walking on street? And i have asked for possibility of walking on water so ...
4answers
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### What's the exact gravitational force between spherically symmetric masses?

Consider spherical symmetric$^1$ masses of radii $R_1$ and $R_2$, with spherical symmetric density distributions $\rho_1(r_1)$ and $\rho_2(r_2)$, and with a distance between the centers of the spheres ...
2answers
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### Are there any exceptions to Newton's laws?

So I am studying the laws of Newton and I'm wondering, are there any deficiencies related to the laws? I mean, somewhere where I can't use them or anything?
1answer
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### Mean value of the force in a collision problem

I have the following problem: A point with mass $m$ and speed $v$ collides with a fixed obstacle and penetrates it, stopping in a space $\Delta x$. Calculate $\Delta t$. I understand the way my ...
1answer
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### How does Baumgartner slow his velocity so that the parachute can open up?

How does Baumgartner slow his velocity so that the parachute can open up? What is Baumgartner's speed just before his parachute opens? What causes his speed to slow down just before the chute opens? ...
2answers
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### Is air drag equation in term of momentum still valid?

This is the known equation of air drag: $$m{\bf a}=mg-\mathcal D=mg-b{\bf v}.$$ Considering this, is air drag equation in term of momentum still valid? $$m{\bf v}=mv_g-b{\bf r}.$$
2answers
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### The Double Integrator: Matching velocity and position as quickly as possible with only a limited amount of force available

If a body with mass $m$ begins at position $x_0$ with velocity $v_0$ and experiences a force that varies as a function of time $f(t)$ (and we ignore gravity, friction, and everything else that might ...
4answers
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### Shouldn't the change in kinetic energy be more in a moving elevator from a stationary frame of reference?

Consider an elevator moving down with uniform velocity. A person standing inside watches an object fall from the ceiling of the elevator to the floor. Say the height of the elevator is $h$. Then the ...
1answer
19k views

### Torque Required For a Motor to Move an Object on Wheels?

I've been attempting to calculate how much torque a motor needs to produce in order to start a stationary object on wheels moving. (The torque is being applied to the rear 2 wheels, the front 2 are on ...
2answers
308 views

### Shoot object into the Sun using minimal energy

Say I want to shoot a cannonball into the Sun with minimal energy (minimal initial velocity relative to Earth). In which direction do I shoot it? Let's neglect Earth's gravity, if that would make ...
1answer
730 views

### Propeller modelling

I need a (very) approximate model of a propeller on an aircraft. My principal question is this: what would the relationship be between: Propeller rate of rotation Aircraft speed Force generated by ...
1answer
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### Force exerted on a cone

This is probably a pretty elemental question, but I can't figure out what the concept is called or how to calculate it. Say you have a solid cone shaped piece of ice, you hold it in your hand and ...
1answer
955 views

### Transform torque from Euler angles to infinitesimal Cartesian rotations

For a certain pair of rigid bodies, I have the gradient of energy in terms of Euler angles. I want to transform this gradient to the gradient of energy in terms of rotations about the $x, y, z$ axes (...
1answer
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### Weightlessness on Earth

Would the following work? Imagine one would 1) create a straight 4000 km long tube (at ground level), following the curvature of the Earth, wide enough to hold a pod the size of an aircraft cabin; ...
1answer
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### Car tires wearing in dependence on breaking system

Lets say I have two cars. They are identical in every way, except that Car A has a normal breaking system, where most of the breaking power is inflicted on the front wheels, and some on the back, and ...
3answers
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### In projectile motion, what does it mean for the motion along the $x$ and $y$ axis to be independent?

In projectile motion, what does it mean for the motion along the $x$ and $y$ axis to be independent? This question is referring to the concept of projectile motions.
2answers
842 views

### Why does gravity assist transfer twice the planet's velocity?

In orbital mechanics and aerospace engineering a gravitational slingshot (also known as gravity assist manoeuver or swing-by) is the use of the relative movement and gravity of a planet or other ...
5answers
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### Forces acting on a point mass in a spinning rigid body

I have learned that all spinning objects will continue spinning even if no force is acting on it, and the tendency to do so is called moment of inertia. But I wonder about the fact that a single point ...
2answers
179 views

### Could Jupiter's gravity destabilize Earth's artificial satellites over a long timescale?

Could Jupiter's gravity destabilize Earth's artificial satellites over a long timescale? After all, it can destabilize Mercury's orbit, and it can also destabilize orbits in the asteroid belt.
1answer
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### Combining Proportions to get Newton's Law of Universal Gravitation

I've read a little on the history of Newton's Law of Gravitation and noticed that the formula can be separated into 3 distinct parts that lead to the end result of $F_g = G \frac{m_1 m_2}{r^2}$; the ...
2answers
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### Why is the center-of-mass of 2 bodies at the focus of their elliptical orbits?

Why is the center-of-mass of 2 bodies (which interact only via Newtonian gravity) located at a focus of each of the elliptical orbits? I know that when there are no external forces, the center of ...
3answers
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### How can I modify the bullet trajectory based on the ballistic coefficient? [duplicate]

Possible Duplicate: How to modify the bullet trajectory based on the ballistic coefficient? I am new to the physics surrounding bullet trajectory and how it is calculated. I am a software ...
2answers
17k views

### Contact force betweeen 2 objects

Suppose that we have 2 objects next to each other.The object at the left is A and the object at right is B.now we have these situations: 1) we push B to the left. 2) we pull A to the left.(in this ...
2answers
259 views

### Are orbits interior to Jupiter's orbit less stable than orbits exterior to Jupiter's orbit?

Or in other words, are there differences in average Lyapunov timescale between orbits interior to Jupiter and orbits exterior to Jupiter? I'm trying to answer a question at http://www.quora.com/Why-...
1answer
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### particle accelerator in space

I'm attempting to learn special relativity and i'm having trouble calculating velocity and momentum for each part of the system after interactions. I wanted to know how fast a linear accelerator and ...
1answer
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### How to get energy of collision if you know force of gravity of an object($m \rightarrow F=mg$)?

How to get energy of collision if you know force of gravity of an object($m \rightarrow F=mg$)? You get energy of collision by kinetic energy $E_k= \frac{1}{2}mv^2$, but if you use just force of ...
1answer
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### Finding orbital eccentricity

I have this problem: They give me, from a satellite that is in orbit in earth, a value for the period, and the closest height to earth surface, the ask me what the eccentricty of the orbit is. I have ...
1answer
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### Calculation of torque for motor used in 4 wheel robot [duplicate]

Possible Duplicate: Torque Required For a Motor to Move an Object on Wheels? I want to build a 4 wheel robot. the maximum weight of the robot is approximately 100 kg. and the radius of my wheel ...
2answers
2k views

### Kinetic energy of a cylinder

It is a long cylinder (you can approx $R=0$), and it has a fixed point in one os its ending points, it's rotating on a plane and I have to calculate the kinetic energy from reference systems situated ...
1answer
404 views

### Spring extensions

A certain spring has attached to it a mass of 25 units: on increasing the load by 6 units it extends 2.5 cm. a) What is the time of oscillation under the original load? b) What will be the ...
2answers
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### Can Vesta dominate the orbits of other asteroids?

I think I remember a talk where a professor said that Vesta is a particularly important asteroid because its gravity is strong enough to perturb other asteroids. In spite of Vesta's size, this effect ...
2answers
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### Investigating damped Harmonic Motion in a Spring?

I'm going to conduct an investigation into the dampening of a spring. Essentially, what specific factors could be investigated? Currently I'm planning to investigate the effect of changing the mass ...
3answers
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### How can a vertical force cause motion at an angle?

I just started learning physics 3 days ago and am having trouble understanding what I am doing wrong. Can someone please explain my error(s)? Thanks! We have a 1kg object on a plane at a 30 degree ...
2answers
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1answer
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### exercise concerning the inclined plane

I have an exercise to ask yourself. A ball of mass m = 5 g starts at rest and travels 50 cm along a ramp inclined at 45 ° to the horizontal. a) If we imagine frictionless motion of the ball along the ...
1answer
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### Equation for the trajectory of a frisbee?

I'm the lead programmer on a FIRST robotics team, and this year's competition is about throwing Frisbees. I was wondering if there was some sort of "grand unified equation" for Frisbee trajectory that ...
2answers
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### Work done by the air resistance [closed]

A ball of mass 0.37 kg is thrown upward along the vertical with a initial speed of 14 m / s, and reaches a maximum height of 8.4 m. a) What is the work done by air resistance on the ball? b) ...
1answer
213 views

### what is the translational motion with the velocity of the center of mass?

and that is the internal motion relative to the center of mass? could give me some examples? desire to relate since I need to find out what is the kinetic energy in the center-of-mass of two particles,...