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.

learn more… | top users | synonyms (3)

1
vote
1answer
41 views

Center of mass of an arc

A very thin tube shaped like a quarter of a toroid has one end attached to the origin $(0,0,0)$ and the other end at $(R,0,R)$. Determine its center of mass. So obviously $y_G = 0$. Using Pappus ...
1
vote
1answer
26 views

Electricity problem [closed]

• Two small metallic spheres, each of mass 5 g, are suspended as pendulums by light strings from a common point as shown in Figure. The spheres are given the same electric charge, and it is found ...
0
votes
1answer
74 views

A child swinging on a swing in sitting position and then stands up

I have one doubt which is that while swinging in sitting position if I all of sudden stands up on that sitting position and then started swinging with that same energy then does my time period will ...
1
vote
2answers
51 views

What is the connection between Newton's laws of motion and his law of gravitation?

What is the connection between Newton's laws of motion and his law of gravitation? Is there a connection where one suggests the other, or are they just two separate ideas that are assumed to be true? ...
3
votes
1answer
45 views

Free body diagram when forces are not directly in contact with the object

I was trying to use Newton's second law to describe the motion of the following pendulum: However, I was confused as to how to include the spring in Newton's second law. I was able to set up a ...
0
votes
2answers
39 views

Potential Elastic Energy between two carts [closed]

I have a problem in which two carts are attached by a compressed spring. I have found that cart $A$ moves at $1.1~\mathrm{m/s}$ to the right and has a mass of $0.39 ~\textrm{kg}.$ Cart $B$ has a mass ...
0
votes
1answer
76 views

Speed of satellite when it falls freely on the surface of the earth [closed]

I am a high school student in my final two years before university. I have a question which I do not know how to approach. Any help would be appreciated. Thanks! "If an artificial satellite is ...
0
votes
2answers
75 views

How do we feel fictitious forces?

Fictitious forces arise because of the acceleration of the frame of reference itself. No real forces act on the object, still the object accelerates. So why it is said that if the earth were to ...
0
votes
1answer
47 views

Gravity and Newton's 2nd law

I started to wonder what would be different when opening e.g. a very heavy door (e.g.m=10 tons) of a safe here on Earth and on the Moon. Lifting (!) the door (taken of its hinges) straight up here on ...
0
votes
1answer
46 views

Solidifying understanding of centrifugal force at the equator vs poles

I'm just trying to get my head around the physics here and understand exactly what's going on, because there's a lot of conflicting information on the internet. Viewed from an inertial reference ...
11
votes
4answers
311 views

Why do smaller animals survive falls from larger heights?

I remember thinking about this classic problem with my friends back in school and tried to work through it again from a physics point of view. It turned out that it is more complicated that I thought: ...
1
vote
1answer
47 views

Calculating orbits with varying laws of physics? [closed]

The general way planets orbit stars in our universe is determined by the inverse square law and the three laws of motion. Both the inverse square law and the three laws of motion are the reason that ...
0
votes
1answer
97 views

Normal Force in Circular Motion

In the above diagram, sec1(on the left side), an object of mass $m$, after releasing from rest from a slant track, continues into a vertical circular track. At a random position on the circular ...
0
votes
2answers
42 views

Momentum when a people fall down to ground (Related to momentum, gravity, lever)

According to the Newton's laws, free fall is subjected to the pull of gravity at acceleration of 9.8 m/s per second. (Something like this) But I don't think the principle of "free fall" is applicable ...
0
votes
1answer
29 views

Solving for the initial height of a projectile

The problem is stated as follows; A cannon is placed at the edge of a cliff at an angle of $30^o$ (With respect to the x-axis) and fires a projectile with initial velocity of $20 m/s$. The ...
0
votes
1answer
39 views

Explaining faster spinning without using conservation of angular momentum

Lets take a very big rotating star ,after the finish of the nuclear fuel the star is going to contract under its own gravity.Now to conserve its angular momentum the star is going to rotate faster. ...
-2
votes
1answer
33 views

Proper explanation of the hydraulic lift [closed]

How is hydraulic lift useful? According to energy conservation it is not possible. Can somebody please explain how a hydraulic lift works?
-3
votes
1answer
28 views

A car with mass 840 Kg is rolling at 50ms^-1 and is suddenly opposed by a friction force of 120N [closed]

A car with mass 840 Kg is rolling at 50ms^-1 and is suddenly opposed by a friction force of 120N. a) Find the Acceleration. b) How long does it take the car to stop. c) How far does ...
1
vote
3answers
76 views

Can a submarine be powered by a wind turbine?

This is not intended as a realistic way for propulsion of submarines, it is just an interesting thought experiment. Say I want to travel directly towards the wind, only powered by the wind. This is ...
-1
votes
2answers
32 views

When I kik a ball at velocity Vo, angle alpha, from the ground..(no air resistance) [closed]

I have the force acting on the ball equals to F = (Fx,Fy) = (0, -mg)? I mean I understand that I have the mg force on the y axis, pointing down, and I understand that there is no additional force on ...
0
votes
0answers
37 views

Car wheel's “slip ratio” equation for game

Some of you may know about slip ratio. It is specific ratio that kind of depends on wheel rotation speed, radius etc. and affects friction. Car has the most friction at around 0.05-0.1 slip ratio ...
0
votes
1answer
32 views

Why does the co-efficent of friction between plane and body does change depending on the angle of the plane?

First of all I know there is a similar question to this one. However, it didn't help me resolve my problem. Let's say there is a body on a angled plane and the system is in equilibrium (the body ...
0
votes
1answer
55 views

Which requires less energy, complete mechanical breaking or vaporization of matter?

Let's say we have a one kilogram piece of rock. Now if we want to separate each molecule from the other molecules making this piece of rock, which method requires the least energy while neglecting ...
1
vote
0answers
37 views

Two Dimensional Momentum [closed]

[2] []3> A tennis player receives a ball of mass $60\ \mathrm g$ travelling horizontally at $55\ \mathrm{ms}^{-1}$ perpendicular to the net, and returns it at $28\ \mathrm{ms}^{-1}$ in a direction at ...
1
vote
1answer
30 views

Speed of pinewood derby car

If I drop a pinewood derby car from 4 feet I know it hits the ground in half a second at about 10.6 mph. If it rolls down the track (starting at 4 feet) it takes longer, but is it possible for it to ...
0
votes
3answers
72 views

What happens when two balls collide? [closed]

What happens when ball traveling at constant speed hit resting ball with same mass more mass less mass (ie. how diagram of balls speeds looks like) Balls are made of same material and they ...
2
votes
2answers
60 views

What happens to a body if it rotates extremely fast?

I am thinking on a object, e.g. ball or planet that starts rotating with increasing speed. Let's assume that his speed get's closer to the speed of light, what happens to this object? There are ...
0
votes
2answers
64 views

How is water falling from a tap an example of the conservation of mass?

In a book, Conceptual Physics by Benjamin Corral, it was given that when water falls down from a tap, it is a case of conservation of mass. They said that this is because water is thick when just ...
0
votes
5answers
114 views

If I push or hit an object in space will it rotate or move along a straight line?

If I push or hit an object in space (vacuum and no gravitation) in direction what is not going trough its centroid, will it rotate or move along in straight line? I expect that on earth it will ...
0
votes
2answers
45 views

Confusion over basis sets in quantum mechanics

In a sense, I feel like I understand every step in the following (fairly typical) calculation, but I don't understand the conclusion. I consider a vector space spanned by two basis vectors ...
-1
votes
6answers
144 views

People went down two different length slides end up at the bottom at the same time [closed]

Discussion I am having: If there are two slides that are at the same height. One slide is 100m long and the other slide is 200m long. The endpoint and start point are the same displacement. In ...
0
votes
2answers
44 views

Confusion in understanding the derivation of wave speed from Newton's Second Law

In the book 'Principles of Physics' by Resnick,Halliday and Jearl Walker,the opening para of derivation of wave speed from Newton's Second Law is such: Let us consider a symmetrical pulse moving ...
2
votes
2answers
144 views

What is the Benefit of Plotting a Log of Net Force vs. Log of Acceleration Graph?

In preparation for a quiz, I've been going over a set of sample questions. One question in particular asks that if I am to graph the logarithm of the horizontal net force of a system vs the ...
0
votes
2answers
45 views

Free falling object with air resistance, what's the velocity as a function of time?

So, I'm looking into how velocity can be represented as a function of time when the air resistance is also function of velocity. The force of drag is $$ F_d = C||\vec{v}||\vec{v} $$ where $C$ is an ...
0
votes
1answer
70 views

Navier Stokes : what about angular momentum?

I play with CFD for a while, and suddenly, a transcendantal question raises: :-) Navier Stokes is basically Newton applied on a continuum in Eulerian. For solids, we would consider linear, but also ...
1
vote
0answers
27 views

Does a potential of interaction produce also torque?

I have a system of particles (spheres with masses and radii), with $6$ degree of freedom (they are free to move and rotate as they wish). Between each couple there is an interaction potential $V(d)$, ...
2
votes
1answer
27 views

What information does kinetic energy and work give us about a body?

When I studied momentum I learned that momentum says about a body how hard is it to stop it. In addition, I learned that impulse tells us in some way how much time would I need to stop the object. If ...
1
vote
1answer
27 views

Applicable force at constant velocity [closed]

For a body moving at a constant velocity, the force $F_{net}=ma$ Since acceleration is 0, $F_{net}=0$ (i.e force applied = resisting force) Since force applied and resisting force are equal, will ...
1
vote
0answers
15 views

Newton's laws of motion! [duplicate]

The first law says that Every body continues to be in its state if rest or of uniform motion in a straight line unless compelled by some external force or otherwise. The second law says that The ...
-6
votes
1answer
43 views

Simple harmonic oscillators [closed]

A block whose mass m is $680$ g is fastened to a spring whose constant k is $65$ N/m . The block is pulled a distnce $x=11$ cm from its equilibrium postion at $x=0$ cm on a frictionless surface and ...
0
votes
1answer
17 views

Why doesn't Torque of masses on a pulley depend on the friction between the rob and the pulley according to a question in the physics 1 book

What I don't understand about this question is: why is the torque of the masses on the pulley equals the weight of each mass times the radius. I thought that the torque on the pulley from the ...
0
votes
5answers
87 views

If “For every action there is an equal and opposite reaction”, why does a gun not injure the shooter's hand?

If "For every action there is an equal and opposite reaction", why does a gun not injure the shooter's hand? Would not the "equal and opposite reaction" of firing a bullet be the kickback the shooter ...
0
votes
1answer
64 views

Gravitational force between rod and mass $m$

Why do we integrate along the whole length while finding the gravitational force between a object of mass ($m$) and a rod of length $L$ and mass $M\,?$ Can't we simply use $F=\frac{GmM}{r^2} \, ?$
0
votes
1answer
34 views

The dot product integral in the proof of the Parallel axis theorem

The first picture is a question about proving the Parallel axis theorem and the second is the solution. I have no problem with the solution except for the part which says that $$ \int 2\vec h ...
-1
votes
1answer
58 views

Conservation of momentum wrt center of mass

"A person with mass m is sitting on one end of a lifeboat of uniform density. Mass of lifeboat is 3m. The person then walks a distance of L to the other side of the lifeboat. Which of the following ...
0
votes
1answer
39 views

“Mass is a measure of an object’s ability to resist motion or movement of any kind”

This statement is presented as wrong, but I dont understand why. Specifically, what is the diff between motion and "movement of any kind"? Its to do with a question about inertia. I understand that ...
1
vote
0answers
32 views

Assumptions in two balls falling experiment

A typical undergraduate physics class problem to demonstrate the effects of conservation of momentum is to have two balls of different mass falling one above the other (the largest mass below) to the ...
1
vote
1answer
43 views

Does a capacitor experience a Newtonian reaction when being charged?

Say I have a capacitor that is being charged with a battery. There are two wires, one on the positive and one on negative terminal of the battery which go to a capacitor. During the charging, a ...
3
votes
0answers
42 views

Elastic collision / relative velocity problem [closed]

I'm having some trouble with a homework exercise and I'd really appreciate some help! I've done the first part correctly (according to the solution sheet), but I can't seem to get the second part ...
2
votes
1answer
36 views

A couple of questions regarding work to velocity exchange [closed]

I was tasked to express the velocity of the cube of mass $m$ at point B using the constants given in the picture below. Friction could be ignored, and the cube could be presumed to reach B with the ...