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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Second Law of Dynamics and Pulleys

The system in the figure is initially at rest . If the system starts to move , evaluate the acceleration of the block $A$. Mass of the block $A$ is $m_A = 60\;\mathrm{kg}$ ; mass of blocks $B$ and $C$ ...
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3answers
72 views

Why does weight on Earth have a tangential component?

I read in Pulsar's answer of this question that weight has a tangential component due to the rotation of the (assumed spherical) Earth but I don't understand this. Can someone expand on it please?
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1answer
43 views

Friction in circular motion?

Let us imagine a car (or just a block) moving in uniform circular motion with radius $R$ with velocity $v$, on a flat surface. It is obvious that friction is the only force capable of providing the ...
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1answer
1k views

Understanding the math behind a falling object attached to a parachute

I'm trying to understand the mathematics behind calculating the total speed and force of a $40 kg_f$ object hooked up to a parachute, falling to Earth. From what I understand, the formula for this is ...
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0answers
25 views

Seesaw pendulum period

If I have a rigid pendulum of length $L$, with the pivot point set somewhere along $L$ and a mass at each end how do I calculate its maximum speed and its period? I want to make a counterbalanced slow ...
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1answer
30 views

Weight Detection Under Concrete/Asphalt [closed]

Consider that a weight sensor was embedded in a road. Would cars that drive over it trigger the sensor? I was thinking it'd look something like this (if we ignored the downward force that the ...
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0answers
13 views

Cohesion Sliding Resistance meaning

What do we mean by "Cohesion Sliding Resistance"?? and how to calculate the value for the same for an iron object placed on a concrete surface for example? P.S.: All I know is this has the units of ...
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2answers
87 views

Equal transit time fallacy and Newton's laws of motion

I've seen the equal transit time theory being used to explain aerodynamic lift [basis is Bernoulli's principle] several times. However recently I've been told that there is NO physical compulsion for ...
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6answers
7k views

Why is the Moon considered the major cause of tides, even though it is weaker than the Sun?

You have likely read in books that tides are mainly caused by the Moon. When the Moon is high in the sky, it pulls the water on the Earth upward and a high-tide happens. There is some similar effect ...
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3answers
3k views

Speed of a fly inside a car

A couple of weeks ago I was travelling in a car (120 km/h approximately) and I saw a fly flying in front of me (inside the car, near my nose, windows closed). I wonder how was that possible. Does it ...
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1answer
48 views

Newton's 1st law [closed]

If all of a sudden the gravitational force and gravity disappears then the planets would still continue to rotate and revolve ? Give reason
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1answer
1k views

Is running in a zigzag helpful in avoiding being shot by an arrow? [closed]

Two people A and B start at a certain point. B runs away from A to another point. A shoots arrows at B. Is it helpful for A to run in a zigzag rather than in a constant direction? To be more ...
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1answer
65 views

Dynamics of pairwise distances in the $n$-body problem

Consider the $n$-body problem where we are interested in describing the time evolution of $n$ masses interacting through a potential $U$. Let $D$ be the matrix containing all pairwise distances ...
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1answer
20 views

Reducing coefficient of friction by vibrations?

Very simply put, if one places a block of some material on a level surface and pushes it horizontally, a certain coefficient of friction is measured. If one tightly couples an oscillator of some sort ...
0
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1answer
44 views

Kinetic energy of a Tesla model S discrepancy

According to Tesla, the model S weighs 1961 kg and uses 237.5 watt hours (855000 Joules) to drive one km. However, when I plug this amount of energy and 1000 meters into the formula W=FD, I get the ...
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3answers
165 views

Does the work done by a person equal the work done on the object in this situation?

If you applied a constant force over a floor that has friction on an object, would the work done by the person equal to the work done on the object? Assume that the floor is flat and that the object ...
3
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2answers
65 views

How deep does a gravity well need to be to remove particles from a planetary body?

I almost considered asking this question on WorldBuilding, however I wanted the brute mathematics on the subject, so please excuse the theoretical nature of this question. I understand the basic ...
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0answers
74 views

In the equation $F = kma$ , what's $k$? [duplicate]

Actually I want to know that what is $k$ & why it's SI unit is set to 1. Also if it's can be expressed in SI units , that means it can be converted into CGS etc. units .. So what's the value of $k$...
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2answers
141 views

Does a scale weigh a bee flying inside a box?

This question is very similar to this one or even this one except some minor differences. The box is much larger than the bee. The box has no top cover. The bee is flying still in the middle of the ...
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1answer
447 views

How to derive the time period equation for a spring mass system taking into account the mass of the spring without involving energy analysis?

I want to know the way to derive the time period equation of a spring mass system accounting for the mass of the spring but not using the energy analysis method but by proceeding in the same way as we ...
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0answers
33 views

How much velocity can a canister of fuel give a spaceship? [closed]

We could approximate a basic solution If we know the mass of the fuel $m$, the mass of the ship $M$ and the amount of energy left in the fuel $E$. So the energy density of the fuel is, $\frac{E}{m} = ...
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1answer
231 views

Can two bodies of different mass attached at ends of string passed over a frictionless pulley produce equal tension on both sides?

In my textbook there is given a case that to calculate acceleration and tension produced in string when string is attached at it's ends with two bodies of masses such that $m1>m2$ and the tension ...
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0answers
37 views

Acceleration mass graph of constant force

If the same horizontal force is applied to objects of different mass. Which graph explains the experimental results. My logic was that since $$ f = ma $$ Is a linear equation it will be a straight ...
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2answers
47 views

Harmonic motion equation - non-null right hand side

Considering the following motion equation : \begin{equation} \ddot x + \frac{a^2 b^2}{c^2} x = -V \frac{a b}{c^2} \end{equation} where $a$, $b$, $c$ and $V$ are all constant. One can identify the ...
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1answer
71 views

Observation and deduction about a stick

Given a horizontal stick AB and a string, of course a stick that is hang on the string in its center of mass is in equilibrium. This is a fact that we take as rule because we can observe it, right? I ...
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1answer
151 views

Derivations of Newton's laws?

I feel convinced that the mathematics behind newtons laws can be derived from Noether's symmetry theorems. The fact that displacement s can be described by a cartesian coordinate system with a ...
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1answer
44 views

If the applied force is constant, what is the graph of the velocity?

This is a sample interview question from Oxford: A ball, initially at rest, is pushed upwards by a constant force for a certain amount of time. Sketch the velocity of the ball as a function of ...
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1answer
15k views

Would a light or a heavy ball roll fastest down a slope?

A small, light ball and a larger, heavier ball are released from the top of a slope. Which will move further? which will come down faster?
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2answers
1k views

Energy needed for Superman to take off and fly at the speed of sound

I just watched "Man of Steel", and I'm wondering if my logic is correct. Let's assume Superman is 80 kg. The energy required to take off from the rest to reach the speed of sound in air (if I neglect ...
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2answers
129 views

How the standard units for length force and time are defined in US Customary Units as standard units are defined in SI?

I'm much confused about US customary units so I want to ask a lot more questions under single question.First how standard units ,in US customary Units,of force time and length are defined as second or ...
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2answers
52 views

Accelerated frames conceptual doubt [closed]

This thing has baffled me for a very long time and therefore I had to ask it here. I was thinking about accelerated frames. Lets assume I am sitting in an elevator going upward with some acceleration ...
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0answers
55 views

Potential Energy = mgh. What is the name of this principle and did Newton discover it?

Somebody I know keeps trying to convince me that Potential Energy $PE=mgh$ is one of Newton's Laws (as well as the closely related idea, Work Done = force x distance moved). I am fairly certain that ...
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1answer
14 views

Calculate velocity $v$ [closed]

A lorry of mass $3.5\times10^4\text{ kg}$ attains a steady speed $v$ while climbing an incline of $1$ in $10$ with its engine operating at $175$ kW. Find $v$. $g=10ms^{-2}$. Neglect friction. The ...
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1answer
80 views

What happens if you fly a drone inside moving passenger airplane? [duplicate]

I have a little question. If I mark an X in the center of a passenger airplane, and try to fly a drone from the X mark in the moving passenger airplane (800-900 km/h), what will happen to the drone? ...
3
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2answers
1k views

Does a pivot exert an additional force, normal to the centripetal force, on an object rotating about it?

A thin plank of mass $M$ and length $l$ is pivoted at one end. The plank is released at 60$^{\circ}$ from the vertical. What is the magnitude and direction of the force on the pivot when the plank is ...
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3answers
117 views

Velocity of a body in a pulley problem involving a spring fixed to the ground

So the picture shows the whole situation. My question is, how do you find the velocity of the object after it had descended 10 cm (0.1 m) ? Pulley's radius 0.2 m, moment of inertia 0.2 kg/m I have ...
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1answer
284 views

Rotating platform with pulleys and stacked blocks

This was a practice test question. Consider the following figure. (If the frictional coefficients are unclear, between A and B we have $k_1 = 0.3$, B and platform is $k_2 = 0.2$. If you further ...
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2answers
114 views

If you lift something does the internal energy increase or remain unchanged?

So change in internal energy $\Delta U = q + w$; so in lifting an object you do work on it, thus increasing its internal energy. Is this correct? Sorry if this is a stupid question.
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2answers
62 views

Free fall vs throw with air resistance

If I let a stone drop from a certain height and throw a stone from a certain height, with air resistance, which will reach the ground first? When I draw a free body diagram the air resistance in the ...
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3answers
65 views

Tension in a string with pulley and two objects at opposite ends

Tension is confusing me. According to my understanding of tension the tension in a string is uniform but while going through the solution of a problem I read that tge tension on the left part of the ...
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0answers
5 views

Acceleration as a function of time in Newtonian gravity [duplicate]

In Newtonian gravity, you have acceleration as a function of separation distance $r$ as $a(r) = GM/r^2$. I need to derive acceleration as function of time, i.e. $a(t)$. PS I got into this when I ...
1
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1answer
197 views

Coriolis Effect vs airplane

So, if I build a highway from north pole towards equator and sit in a car, speed pretty fast towards it, I should feel force with the Earths rotation due to the different rotation speeds of this ...
2
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1answer
44 views

Cable wakeboard raley

Illustration of the problem: http://www.youtube.com/watch?v=OWRixptJaRo The non physics solution: http://www.youtube.com/watch?v=FRwHcJjfCR4 My first approach to learn this was to follow youtube ...
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0answers
56 views

Find the Kinematic degrees of freedom of the following contraption

In the above mechanism it is required to find the generalized coordinates to write equation of motion of the MDOF system. I just want to ask how do we actually approach such a problem? How to identify ...
0
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1answer
36 views

Newtonian mechanics, block on conveyor belt [closed]

The coefficient of friction $\mu$ between the block and the conveyor belt is $0.3$ and the belt is moving with a speed of $6m/s$ when a block is dropped onto it from rest. Find the time when the ...
0
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1answer
25 views

The directions of the frictional force acting on the cylinder while ascending and descending cylinder

A cylinder rolls up an inclined plane,reaches some height,and then rolls down without slipping throughout these motions.The directions of the frictional force acting on the cylinder (A)While ...
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1answer
127 views

What's my $\mathrm dM$? Gravitational Potential inside a circle of mass

I'm trying to find the gravitational potential for an arbitrary point within a ring of uniform mass density. The point is constrained to be in the same plane as the ring. So we start with: $$\Phi=\...
3
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2answers
2k views

Average Force vs Net Force

The F in $$Impulse = F*t$$ is said to be the average force. For a ball dropped vertically onto a horizontal surface, the average force, F, on the ball from the floor is: $$F = \frac{\Delta{p}}{t}$$ $$\...
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2answers
49 views

Friction, Dynamics question

In the given question $F=2t$ where $t$ is time in seconds for which the force has been applied. Friction exists only between $A$ and $B$ with coefficient of friction $\mu=1/2$. Here we can easily see ...
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12answers
2k views

Is the distance between the Sun and the Earth increasing?

M = mass of the Sun m = mass of the Earth r = distance between the Earth and the Sun The sun is converting mass into energy by nuclear fusion. $F = \frac{GMm}{r^2} = \frac{mv^2}{r} \rightarrow r =...