# 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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### 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 ...
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### How to find equation of motion for this trajectory? - object leaves curved ramp at a given velocity [closed]

Here is the sketch: The sketch is supposed to be side-view of the path of the object. The following values are known: $r$ - radius of the circle that describes the path AB of the object $a$ - ...
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### Does a ski racer with a larger mass have an advantage?

Does a ski racer with a greater mass have an advantage over a racer with a lesser mass? If mass of one racer is 54 kg and the mass of a more slender racer is 44 kg I know the speed at which they ...
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### Newtonian physics vs Special relativity - what is the most “relative”?

This might be a question purely of words and the meaning of them but isn't Newtonian physics more "relative" than Einstein's Special relativity? Newtonian physics predicts that laws of momentum & ...
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### What is the typical orbital life of an artificial satellite?

The orbit of satellites around Earth eventually decays, or so I read. This is typically caused either by atmospheric drag, or by tides. I would assume most satellites have a limited service life in ...
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### What will be the relative speed of the fly? [duplicate]

It has happened many times and i have ignored it everytime. Yesterday it happened again . I was travelling in a train and saw a fly (insect) flying near my seat. Train was running at a speed of ...
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Two balls, first with the mass $m_1$ and the second with the mass $m_2$ are falling from the heigh $h$. Suppose all the collisions are perfectly elastic and do not consider the size of the balls. $m_1 ... 2answers 652 views ### Newtons Third Law [duplicate] In Newtons Third Law, it states that for every action, there is an equal but opposite reaction. So that means tat for every action, there will be a reaction to cancel it out. So if that is the case ... 7answers 6k views ### Does juggling balls reduce the total weight of the juggler and balls? A friend offered me a brain teaser to which the solution involves a$195$pound man juggling two$3$-pound balls to traverse a bridge having a maximum capacity of only$200$pounds. He explained that ... 6answers 10k views ### Could we send a man safely to the Moon in a rocket without knowledge of general relativity? I'm wondering if it's possible to send a man to the Moon using equations consistent with Newtonian gravity and without the elaborate tools of Einstein gravity. Are the predictions made by Newtonian ... 5answers 6k views ### How am I able to stand up and walk down the aisle of a flying passenger jet? The energy of a moving object is$E = mv^2\;.$That is it increases with velocity squared. I walk at say 3 miles per hour, or lets round that down to 1 meter per second for a slow walk. I weigh less ... 6answers 5k views ### Is the energy conserved in a moving frame of reference? Consider this situation: When the box is at the bottom of the frictionless incline, it will have a velocity of$v_f$. The person is an inertial frame of reference that moves at a constant ... 5answers 6k views ### Why are a motorcycle's front brakes more effective than back? I've noticed that when I apply the front brakes on my bike it stops quite quickly. If I apply the back brakes at the same speed, it skids rather than stopping quickly. Why? 6answers 891 views ### Is Newton's first law something real or a mathematical formalism? Why do objects always 'tend' to move in straight lines? How come, everytime I see a curved path that an object takes, I can always say that the object tends to move in a straight line over 'small' ... 7answers 7k views ### Why do we fall down when the bicycle slows down? [duplicate] My question is: It is easy to balance a bicycle when it is moving at a fairly high velocity, say 7 m/s or 25 km/hr. But when a bicycle slows down, it is hard to keep it upright, and the person riding ... 2answers 3k views ### Slinky base does not immediately fall due to gravity Why does the base of this slinky not fall immediately to gravity? My guess is tension in the springs is a force > mass*gravity but even then it is dumbfounding. 4answers 532 views ### How can tangential acceleration from a radial force be explained? A mass is attached to a rope, and put into a circular motion. If I pull the string from the center, the tangential speed of the mass will increase (by conservation of angular momentum). I am ... 4answers 1k views ### Is the second law of thermodynamics a fundamental law, or does it emerge from other laws? My question is basically this. Is the second law of thermodynamics a fundamental, basic law of physics, or does it emerge from more fundamental laws? Let's say I was to write a massive computer ... 3answers 863 views ### How can I relate linear and angular motion using a single formula? I want to relate linear and angular motion using a single formula. Assume I have a 10m rod, and I apply a force of 5N on it, 2.5m away from the axis of rotation for 1s. How can I determine the ... 3answers 4k views ### Why does the cart move? [duplicate] A while ago someone proposed the following thought experiment to me: A horse attached to a cart is resting on a horizontal road. If the horse attempts to move by pulling the cart, according to the ... 4answers 2k views ### Newton's first law: is his concept of (force of ) inertia still useful and used? The force of inertia is the property common to all bodies that remain in their state, either at rest or in motion, unless some external cause is introduced to make them alter this state. That ... 7answers 856 views ### Distribution of Gravitational Force on a *non-rotating* oblate spheroid Suppose a person is standing on a non-rotating$^1$oblate spheroid of uniform density. He first stands on one of the poles, then on the equator. In which case is the gravitational force greater? In ... 6answers 68k views ### What is the difference between stress and pressure? What is the difference between stress and pressure? Are there any intuitive examples that explain the difference between the two? How about an example of when pressure and stress are not equal? 5answers 503 views ### Infinities in Newtons law of gravity (for point particles) Newtons law of gravity for two particles of mass$m_1$and$m_2$is:$G\frac{m_1.m_2}{r^2}$. Supposing that the particles are point particles then gravitional attraction will bring them closer ... 2answers 1k views ### Accretion disk physics - Stellar formation I was going through the Wikipedia page for Accretion disks, and I couldn't comprehend what the meaning of this is: "If matter is to fall inwards it must lose not only gravitational energy but also ... 2answers 6k views ### block slides on smooth triangular wedge kept on smooth floor.Find velocity of wedge when block reaches bottom Find the velocity of the triangular block when the small block reaches the bottom: Here is what I did: The final velocity(at the bottom)of the small block of mass m is$\sqrt{2gh}$along the plane ... 8answers 21k views ### Is gravity a force and if so what is its opposite? For every force there is an equal force in the opposite direction on another body, correct? So when the Suns gravity acts on Earth where is the opposite and equal force? I also have the same ... 2answers 3k views ### Put a bullet into orbit around the moon While I was watching this beautiful video, the absence of air friction pushed me to ask myself: While standing on the surface of the moon, what is the initial velocity by which you can fire a bullet ... 4answers 4k views ### Static Friction - Only thing that can accelerate a train? I'm a computer programmer that never studied physics in school and now it's coming back to bite me a bit in some of the stuff I'm being asked to program. I'm trying to self study some physics and ... 7answers 8k views ### Is there any true inertial reference frame in the universe? Is there any true inertial reference frame in the universe? Newton's first law states that an object at rest remains at rest, and an object performing uniform motion performs uniform motion, until ... 4answers 1k views ### Why does Newton's third law exist even in non-inertial reference frames? While reviewing Newton's laws of motion I came across the statement which says Newton's laws exist only in inertial reference frames except the third one. Why is it like that? 3answers 5k views ### Projectile Motion with Drag The overall goal is to write a Mathematica program that will compute the launch angle that will yield the greatest range with using [RandomInt] function, but I was having trouble with the physics. In ... 5answers 1k views ### High speed does not kill. Does acceleration do it ? or jerk? In a recent question the OP asked why high speed will not kill us. The accepted answer, highly upvoted, stated very first that Speed doesn't kill us, but acceleration does. The second answer ... 4answers 14k views ### Does a car use friction to move? When a car's engine injects fuel into the cylinder chambers, the reaction creates a force that generates rotational momentum to the shaft and over the transmission, it translates that power to the ... 1answer 657 views ### If a bullet is fired vertically upwards, when it comes back does it fall to the same spot? [duplicate] What I'm basically asking is that if a body is projected with sufficiently high velocity so that it doesn't escape from the earth's gravitational field but reaches an appreciable height with respect ... 4answers 827 views ### Comparing Static Frictions In this figure, which of the static frictional forces will be more? My aim isn't to solve this particular problem but to learn how is static friction distributed . Since each of the rough-surfaces ... 1answer 859 views ### How does Newton's 2nd law correspond to GR in the weak field limit? I can only perform the demonstration from the much simpler$E = mc^2$. Take as given the Einstein field equation:$G_{\mu\nu} = 8 \pi \, T_{\mu\nu}$... can it be proved that Newton's formulation ... 2answers 2k views ### Countersteering a motorcycle Everyone knows the story about countersteering. For those who don't I will explain it below and after the explanation i will ask my question. You can watch this short video as a beginning: ... 2answers 753 views ### Path to obtain the shortest traveling time Asume we have a particle sitting at the point A(0,0) in a gravitational field. (g=9.81) It is going to move along some path to the point B(a,b) Where a>0 and b<0. What is the curve the particle ... 2answers 20k views ### Perfect elastic collision and velocity transfer So my teacher told me that when you have two identical balls in a perfectly elastic collision, the first ball A will collide with B and afterwards A will stop and B continue. Why is this? Doesn't ... 1answer 249 views ### Rigid Body Mechanics In a vacuum (no gravity) [closed] I am writing a physics engine to map the rotary and translatory movements of a uniformly dense solid cylinder within 3d space. If a vectored thrust is applied to one end of the cylinder at an ... 1answer 5k views ### Maximum range of a projectile (launched from an elevation) If a projectile is launched at a speed$u$from a height$H$above the horizontal axis, and air resistance is ignored, the maximum range of the projectile is$R_{max}=\frac ug\sqrt{u^2+2gH}$, ... 2answers 280 views ### If Earth starts moving when attracted by an object, where does the energy come from? Suppose a body(very big but not bigger than Earth) moves against gravitational force of Earth. The force will do negative work on the body decreasing its kinetic energy. The decreasing energy is ... 3answers 302 views ### Leading-order cause of diurnal (not semidiurnal) variations in$g$? The following graph shows the result of a very impressive differential measurement of the gravitational field in Boulder, Colorado, over a period of a couple of days. Floris got it from a ... 2answers 790 views ### Why does a ruler continue to slide after toppling? I was playing with a small ruler by repeatedly toppling it, see diagram below: The ruler, standing$h$tall and approximately a regular bar, is prevented from free-rotating by a fixed ridge (a ... 1answer 2k views ### Use the relative velocity formula to find v2f in terms of v1f? Q: A$0.150\text{ kg}$glider is moving to the right ($+x$) on a frictionless, horizontal air track with a speed of$0.80\text{ m/s}$. It has an elastic collision with a$0.300\text{ kg}$... 2answers 3k views ### Is any work done if I walk in a circle? My friend and I were arguing about this and I was wondering if someone out there could settle this for us. Basically, he and I were walking to buy some stamps. When we were on our return trip he ... 2answers 179 views ### Kinetics energy with different reference frame (a fighter plane shoots a bullet)? Suppose a plane flies at 1km/s and shoots a 2kg projectile at 1km/s, so to the Earth the projectile flies at 2km/s with 2*2*2/2 = 4MJ. The same gun, when fixed on Earth, shoots the same 2kg ... 2answers 587 views ### Pendulum Wave Period Recently I've seen various videos showing the pendulum wave effect. All of the videos which I have found have a pattern which repeats every$60\mathrm{s}$. I am trying to work out the relationship ... 3answers 328 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 ...