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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Conserved quantities in an angular system

Given the following question: A student initially stands on a circular platform that is free to rotate without friction about its center. The student jumps off tangentially, setting the platform ...
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Calculate the applied clockwise couple $M$ which would cause the cylinder to slip [on hold]

Problem: Will the cylinder slip and roll upwards due to applied couple $M$? Or will it slip but stay in its place(rotate round the central axis)?
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19 views

Does Earth also move due to some electrostatic forces?

Does the earth experience some electrostatic forces due to other planets...which also make it move? My question is..whether the earth also moves due to electrostatic force of attraction or only due ...
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1answer
149 views

Why isn't jumping against a wall an elastic collision?

According to this calculator http://www.abecedarical.com/javascript/script_collision1d.html when low mass object hits high mass object it is reflected gaining opposite velocity almost the same as ...
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3answers
146 views

Animating an Acceleration Vector - Acceleration of object on a crested path in gravitational field

So I was reading in Chapter 3 of my textbook, Sears & Zemanksky's University Physics with Modern Physics by Young and Freedman, 13th Edition, and the discussion took us to a definition of the ...
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1answer
37 views

Analysis of motion of a body moving on a string?

I was wondering about something I observed yesterday. To give some background, one of my hobbies is slacklining. This is essentially like tight-rope walking but with a one inch piece of (in this case ...
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Resultant forces on system of particle is zero , we can have?

This is how the specific question is framed? If the resultant of all the external forces acting on a system of particles is zero, then from an inertial frame, one can surely say that: 1: ...
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22 views

a falling object in different areas [on hold]

Why when you're in a moving bus and throwing a ball upward, that ball goes with you until it comes back in your hands, but when you're in a moving van the ball doesn't fall in your hand, but falls to ...
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3answers
54 views

Rain measurement with wind blowing

Rain measuring simple unit with a measuring jar fitted with a funnel collect rain pouring. Here I presume the rain falling vertically down with zero speed. However, usually the wind is blowing. If it ...
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2answers
462 views

How to find the center of mass of several objects in a 2d plane?

We have the following scenario in a 2d plane: a big rectangle with a lot of smaller similar uniform rectangles in it, all of them weight differently. Where is the center of mass of this object ...
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3answers
559 views

Does a heavy body move with the slightest force on a frictionless surface?

If I apply horizontal force on a body resting on the ground, my force will be opposed by the frictional force and the body will accelerate at the point where my force exceeds the force of friction = ...
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229 views

How can a planet gravitationally capture objects?

I would expect that any asteroid or other object originating far away but passing near a planet would pick up speed and energy as it approaches, but unless it comes into contact with the atmosphere ...
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3answers
44 views

Force Body Diagrams of object sliding down ramp

So I think I am confusing myself about forces. I know that when something is sliding down a ramp that it will have the force of gravity, normal force and force of friction acting on it. But for an ...
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1answer
60 views

Can you determine acceleration from positions and velocities only?

I just began reading the Landau and Lifshitz book on classical mechanics. It states on the first page of Chapter 1 that: Mathematically, this means that, if all the coordinates $q$ and velocities ...
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3answers
190 views

Can we rigorously define force?

I'm looking to get rigorous definitions on which to base the important quantities in classical mechanics. To me a "rigorous" physical definition is an operational definition -- that is one in which ...
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1answer
229 views

Is gravitation really a conservative force?

A rotating gyroscope that is mounted in a gimbal maintains its rotational axis relative to space when it is moved – and not to the surface of the earth, as illustrated below (the figure shows only the ...
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1answer
232 views

Why potential energy of external force on particle attached to spring is equal to full force multiplied by full displacement?

I am having quite difficult time to understand the meaning of total potential energy on spring. All references I read say that the total potential energy on particle attached to spring is: ...
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2answers
380 views

Kinematics question - Newton's Law of Motion [closed]

Question: Find the mass M of the hanging block in the following figure which will prevent the smaller block from slipping over the triangular block. All the surfaces are frictionless and the strings ...
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0answers
24 views

Spinning, decelerating coin on a table

A coin spun on a table will eventually end up flat on the table, ignoring the cases where it remains balanced and comes to rest on its edge (or falls off etc). Before the coin comes to rest on its ...
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1answer
22 views

Angular and linear displacement of a turning car

My illustration is supposed to show a simplified car (with just two wheels, where the front wheel has been rotated $-90 \text{ degrees}$). Let the car travel at constant speed. This means that the ...
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2answers
55 views

Free-Falling Object

How does the presence of air affect the rate at which a body falls? What is the rule for falling objects, when there is little or no air resistance?
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2answers
31 views

Inelastic Collision and Energy

How is is possible for momentum to be conserved and for KE to not be conserved? Momentum is related to velocity and velocity is related to KE, therefore if KE was lost, how can the system have the ...
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1answer
31 views

Definition of Force Using Momentum

When we use F = change in momentum / change in time, is that the average force applied? There could be different magnitudes of force applied over time to change the momentum (it could be instantaneous ...
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1answer
31 views

What's the physical meaning of change in momentum vector?

If I there is a initial momentum of 10Ns upwards, and final momentum of 10Ns to the right, I can find the difference in momentum by drawing a triangle and finding the resultant vector. But, how is ...
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0answers
20 views

What is happening kinematically to a car on an icy turn? [on hold]

I am stumped on a conceptual homework question that involves rotational kinematics and friction. Consider a car traveling along a road that encounters a turn covered in an unseen layer of ice. ...
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2answers
53 views

Where do forces point in an equilibrium system

I have the system above, with three identical balls of weight $W$ and radius $r$. The angle joining the centres is $\theta$, and the coefficient of friction between the balls and the plane is $\mu$ ...
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2answers
29 views

Calculating velocity based on applied force

If I have a block sitting on a spring, ignoring air resistance, with 45N of stored elastic energy in the spring, and the block weighs 500g, what would be the process for calculating its maximum ...
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0answers
18 views

Relative Kinetic Energy on Two Sides of a Spring [on hold]

There is a massless spring on a frictionless surface with two objects, $A$ with mass $m$ and $B$ with mass $M$, attached to the ends of the spring. Both objects are pulled and held at a position where ...
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1answer
87 views

When will the Earth stop rotating?

I looked up leap second in Wikipedia. It is a second added (usually) to clocks to keep them in sync with the atomic clock. It said that 25 leap seconds were added in the last 43 years and that none ...
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2answers
178 views

Correct terminology for combined kinematic and dynamic state

The kinematic state is defined as the position and orientation in space. The dynamic state is defined as the associated velocities. What is the correct terminology for the combined kinematic and ...
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2answers
52 views

Mathematics of simplified air resistance

I recently encountered a problem in which when throwing a ball upwards one has to determine whether it goes up or comes down faster when not only was gravity to be considered, but also air resistance ...
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42 views

Two solutions, A+ and A-, for masses connected via springs

My prof gives an example of trying to solve the equations of motion for a series of gliders each connected by springs, with the same spring constant. From looking at the $j-1$ through $j+1$ glider, he ...
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2answers
121 views

Can the coefficient of friction be derived from fundamentals?

It is common to want to derive macroscopic laws from what we know microscopically - after all, given a (correct) microscopic description, everything larger should follow. Has it ever been done to ...
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1answer
282 views

Block Sliding Down a Plane (Perpendicular Velocity)

I'm having trouble understand the concepts for this problem. Here's the problem: A block is placed on a plane inclined at angle $\theta$. The coefficient of friction between the block and the ...
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3answers
94 views

Two questions about the coefficient of restitution

If you were to drop a ball onto a surface from a height $h$ and the ball collided with the surface and then rebounded, would the ball then travel a distance of $eh$ back up from the surface where $e$ ...
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1answer
92 views

Quantum violation of Newton's Third Law? [on hold]

From this site: http://www.learning-mind.com/5-thought-provoking-quantum-experiments-showing-that-reality-is-an-illusion/ I gained the knowledge that a group of scientists, upon measuring a tiny ...
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1answer
29 views

A Question on Friction [on hold]

And yes, this is not a homework thing.Here's my working.
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4answers
512 views

Confused about Newton's 3rd law

I am confused about Newton's 3rd Law. If a person jumps off the ground a force is applied both to the person and to the ground. However, as $F=ma$ acceleration experienced by the Earth is much less ...
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1answer
28 views

Finding radius of turning car to calculate the centripital force

I'm writing a program to simulate a car driving. I'm wondering how I should find the radius when calculating the centripital force. If we let the car travel at a constant speed, then $F_{net} = ...
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0answers
30 views

Initial position and velocity given, force given. Find the trajectory of the particle [on hold]

If a particle of mass m at time t=0 has velocity v = u j position r = -a i Force acting on the particle is F = $-(mv^2/a)$(R/R) (R is the position vector, v is the velocity vector) Find the ...
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2answers
90 views

Computing distance traveled from jerk

When dealing with higher time derivatives like jerk, how does one find the distance traveled? Can it be calculated by just knowing time?
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3answers
116 views

In general relativity, how do we think of Newton's third law for gravity?

In GR everything become geometric, gravity becomes curvature in spacetime. How do we think of Newton's third law in the context of GR? What corresponds to action and what to reaction?
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1answer
23 views

Acceleration of a system [on hold]

I worked out this problem that has two masses and and pulley with one mass hanging and the other sliding across a surface and I had to solve for the systems acceleration. Can someone tell me if I did ...
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1answer
30 views

Pendulum at an angle

A pendulum has a period of $T$ when swinging from a string. The pendulum is now placed on a frictionless incline at a 30 degree angle. What is the new period of the pendulum?
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2answers
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Different directions of frictional force when objects are rolling

My textbook has two instances of rolling bodies (smooth rolling). In the first, the body is rolling on the horizontal floor with some acceleration of its centre of mass. In this case, the book says ...
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5answers
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Why can't a rope be pulled completely straight?

I have found several discussions on how to calculate the sag of rope that is tied off at two points (like a tightrope), and I understand it to a certain extent. What I can't wrap my head around is how ...
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1answer
295 views

Walking and Friction

If walking is a result of the reaction to a kick backwards to the ground (reaction being friction), it appears that it should be true that the kick will have to be less than the kinetic friction ...
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0answers
22 views

Torque due to non-uniform force [on hold]

Suppose a non-uniform force, varying along with the distance, is acting normally on the surface of a rod hinged at the mid point. The force varies along the length of the rod, i.e as we go down along ...
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2answers
32 views

If I flex my arm, where is the “equal and opposite” reaction?

In my sight, nothing happens at all. Is the opposite reaction pressure applied to my bones? It certainly seems so; however, since I flex my arms in a curve, shouldn't the opposite reaction direction ...
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1answer
41 views

Why, in a car taking a sloped curve, friction is perpendicular to the car

In solving the problem we usually use the friction as the centripetal force, but I could never understood how is this possible. I understand that if a car is making a circular motion, some centripetal ...