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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2answers
116 views

All reference frame are inertial? Where is the flaw in reasoning?

This is my first post here. I have a line of thoughts which might be wrong but I couldn't find the error. Suppose we have a point mass subjected to an arbitrary force $F$. In the lab reference frame ...
0
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1answer
43 views

How to calculate the linear momentum on a dumbbell? [closed]

In this picture there is a dumbbell and a mass in motion that hits one of the masses of the dumbbell. Now the problem is I have to find the velocity of the CM and the rotational speed around the CM. ...
-1
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1answer
45 views

Is this differential equation (for damped & driven physical pendulum) physically valid?

Following is the equation of motion for a physical pendulum which is damped and driven by a force of frequency $f$: $$\frac{d^2 \theta}{dt^2} + b \frac{d\theta}{dt} + sin(\theta) = Tsin(2\pi ft)$$ ...
-1
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0answers
22 views

What would be the craziest (but still plausible) plan for launching a small payload to the moon? [closed]

I wonder what would be the cheapest possible (that means cheaper than anything else that's out there already) to "just" launch a small payload (like a ball less than a kilogram) and crash it somewhere ...
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3answers
17k views
3
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1answer
2k views

Why does the beam in a weighing balance get tilted proportional to the weights added to each pan?

I'm talking about a beam balance(a simple weighing balance with a beam and two pans hung on either side) As answered in a previous question, the beam comes back to the original position when one ...
0
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1answer
229 views

How does ground interact with a box rotating around its corner?

I have some questions about how forces $F$, friction force $F_{friction}$, and normal $N$ interact in order to the box below to turn (clockwise) about the red corner, without sliding. The force $F$ is ...
0
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1answer
43 views

Force required to rotate around an axis [closed]

So I have a rather simple physics question that I am not sure where to begin with. I am designing a dumper and I need to figure out the amount of force required to rotate and lift it around a bearing. ...
6
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1answer
320 views

Derivation of Universal Variables

Does anyone know of link to the derivation of the Universal Variables? This is in regards to Kepler's equations. The Wikipedia link didn't have enough information for me, and the Colorado page doesn'...
11
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6answers
3k views

Confusion with Newton's third law

“Every action has an equal and opposite reaction.” I have a query about the word every in that sentence. Suppose we have two objects A and B. A pushes B with a force of 5N and B will push A with a ...
2
votes
2answers
55 views

Energy Stored in Spring [closed]

Area Z represents the energy stored in the spring when it is stretched to a length L I am trying to understand why this is so: $$E = \frac{1}{2}kx^2$$ Here, $x$ is the vertical side of triangle $Y$...
1
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3answers
260 views

Centripetal and centrifugal force

If a stone is rotated with the help of a rope, then both centripetal force and centrifugal force will be liberated. The magnitude of that forces are same, but direction of them are opposite to each ...
0
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1answer
37 views

Acceleration in full-swing pendulum

Consider a $360^{0}$ swing pendulum with a massless rod. If I start it from the position of unstable balance, at the very top of the circumference, according to the conservation of energy, its ...
1
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1answer
51 views

What is the degree of freedom of pure rolling motion?

A cylindrical body is pure rolling, what will be the degree of freedom for it? I am confused between 2 and 1 if slipping occurs than it has 2 but in pure rolling there's no slipping so what will it ...
2
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3answers
129 views

Information about newton's third law

Well I am still small student of physics, but as far as I know, Newton's Third Law states that, "For every action there is equal and opposite reaction." Now let me tell you how I understood ...
0
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2answers
127 views

Few questions related to Tension

I am struggling with the concept of tension in a rope. Below specific questions. I am understanding tension to be an elastic force between rope molecules. If so, is it fair to say the net tension ...
1
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1answer
55 views

Simple Conservation of Energy Question

Deduce that the speed $V$ with which the bullet strikes the plasticine is about $160 \ m/s$ Using the conservation of energy, I equated the kinetic energy of the bullet to the potential energy of ...
2
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1answer
231 views

Torsional spring and Euler angles

I have a question about the moments generated by torsional springs. Consider an inertial reference frame A and a body fixed reference frame B. The frames are connected by 3 rotational springs acting ...
1
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2answers
49 views

System rigidity

What is the meaning of system rigidity in mechanics? I can't understand how to classify the system as rigid or not, and what is the effect of rigidity on the whole system. If you know anything about ...
4
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4answers
69 views

When a person bends forward, does normal reation force change as a component of his weight is applied in torque?

My thoughts :i read that normal reaction is equal to the weight of the person in the case above as the effective vertical force in the system is zero.but im confused cuz a component of the weight is ...
7
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6answers
2k views

Newton's third law and punching a glass or a feather

According to Newton's third law, action force equals reaction force in terms of magnitude. When I punch a glass, the glass punches me back. If I exert a greater force on the glass, it will break. ...
10
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7answers
3k views

Ball flying towards me or me flying towards ball

Suppose a ball is flying towards me at a speed of 10m/s and that, on impact, I feel "x" amount of pain. If, instead, it was me flying towards the ball at the same speed, with all other conditions ...
4
votes
3answers
87 views

Tension in the string [closed]

In the following diagram, what's the force that's acting on $m$, the Tension in the string? There is no friction between $M$ and the ground but there is between $m$ and $M$ and I need to find the ...
0
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2answers
96 views

Finding acceleration in a pulley system

In the above system, mass A is accelerating at $a$ upwards. The question then asks to find the magnitude of mass B's acceleration, in terms of $a$. I know that throughout the massless string, the ...
2
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4answers
129 views

How to apply a force vector to a position vector?

A particle is present in the two dimensional space. It's position is given by the vector: $$x = \begin{pmatrix} |x| \cos(\theta) \\ |x| \sin(\theta) \end{pmatrix}$$ It experiences a force of: $$ F = \...
1
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2answers
41 views

Point object, Kinematics

I am very new to physics. This evening, I was reading about the concept of objects to be considered as point objects under some circumstances. And I was trying to think of circumstances under which ...
2
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1answer
28 views

Outbalancing vibrations

Consider a ship vibrating in the fundamental/principal/first symmetric mode shape (similar to that of a Bernoulli-Euler beam), induced by the main engine (similar to that of a vibration shaker). I ...
1
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2answers
197 views

Breaking Newton's 3rd Law?

I am having trouble explaining how the following experiment actually works, but it does.? Place a neodymium magnet on a piece of Styrofoam and a test tube of water next to it on the same piece of ...
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0answers
37 views

Animating Differential Equations

I was tasked with creating a $3D$ animation in Mathematica, which aims to describe the movement of a football through space as it's kicked. There are several differential equations regarding this ...
0
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2answers
51 views

How to calculate energy loss in a rotating shaft?

Please help me with proper formula for below example. Imagine a rotating shaft 'X' with 2 gear wheels 'a' and 'b' of same dimensions. If energy applied to gear 'a' on the shaft through source A ...
2
votes
2answers
499 views

Escape velocity at an angle

Comparing the work required for a mass to escape the Earth's gravity to the necessary initial kinetic energy gives us the escape velocity from the surface of the Earth of around $11\;\mathrm{km\cdot s^...
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2answers
53 views

Parallelogram Law of Force Addition

In most of the mechanics textbooks , the Parallelogram Law of Force Addition is stated without any justification or an experiment to confirm this law. Also after introducing this law forces are also ...
1
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4answers
75 views

Friction-Newtonian Mechanics

Here we are having two blocks of mass $2~\rm kg$ and $4~\rm kg$ on an inclined angle with angle of inclination being $30~\circ.$ The block of mass 2 kg has a coefficient of friction $\mu_1=0.2$ and ...
0
votes
4answers
189 views

Force exerted on carseats?

Can anyone explain how force is exerted on car seats during a crash? I am being told in car seat safety forums that $force=mass \times acceleration$. So if a $2000 \;\text{lb}$ vehicle bumps you at ...
4
votes
2answers
142 views

Weight Distribution of granular piles

I was recently at a farm watching piles of grain being formed in the shape of enormous cones. Each of these grain stacks weighs in excess of 50 tonnes. I am not a physicist but I am very curious as to ...
0
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1answer
41 views

Collisions; Linear Momentum [closed]

Let's say we got a rough surface with friction and there are 2 blocks, the block of the left has initial velocity and will collide with the block of the right, which is in rest. Consider an elastic ...
1
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1answer
46 views

Note and homework organization [closed]

I am currently in a mechanics class and have some trouble trying to figure out how I should structure my lecture notes and my homework. I recently began rewriting my notes after class but I am still ...
1
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2answers
49 views

Homework: Angular Acceleration from Net Torque [closed]

I have the correct answer but don't know how that is the correct one. My answers were way off which indicates I am missing something big but don't know what. Now the 4 torques are: t1=6.175, t2=....
6
votes
3answers
1k views

Equivalent spring-constant for infinite square grid of springs

Consider an infinite square grid, where each side of a square is a spring following Hooke's law, with spring constant $k$. What is the relation between the force and displacement between two points? ...
0
votes
0answers
49 views

Trouble following an argument about a rocket problem

This is from pages 32-33 of Physics for Mathematicians. A rocket + fuel system of mass $m(t)$ is moving along at velocity $v(t)$, with its fuel being ejected at the velocity (relative to the rocket) $...
0
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2answers
132 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 track, ...
8
votes
1answer
114 views

Experimental data for asymmetric Newton cradle

Using a "successive impact model" (as if each ball were seperated from the other ones), I produced the following animations: You can see any combination of balls with masses of 1 or 2 (left) or 1 ...
1
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0answers
30 views

How to apply conservation of energy to active noise-cancelling headphones?

Active noise-cancelling headphones add the opposite waveforms of the ambient sound in order to cancel out this ambient sound by destructive interference. I do not understand why adding more power in ...
1
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5answers
374 views

Forces and acceleration on rotating objects?

Suppose you have an object undergoing uniform circular motion, with force vector pointing towards the center and another force vector tangential. Can it be said that the net force pointing in the ...
0
votes
1answer
34 views

instantaneous velocity center

The instant center of rotation, also called the instantaneous velocity center is the point fixed to a body undergoing planar movement that has zero velocity at a particular instant of time. For ...
2
votes
4answers
26k views

If something that is moving at constant velocity has no net force acting on it, how come it is able to move other objects?

Let's say 10 kg block is sliding on a frictionless surface at a constant velocity, thus its acceleration is 0. According to Newton's second law of motion, the force acting on the block is 0: $a = 0$...
-1
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2answers
21 views

Cinematics; Equation of movement

What's the difference using the fórmulas v=d/t , or a=v/t, instead of equations of motion? I dont get it.
1
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1answer
174 views

Cause of SHM of liquid-column in V-tube

Suppose there is a v-shaped tube filled with water. The left limb is at $\theta_1$ & the right limb is at $\theta_2$ with the horizontal base. Initially, the level of water in both the columns are ...
1
vote
1answer
120 views

Why are trains so hard to stop?

Since there are brakes on every car, shouldn't the stopping time of the entire train be the same as the stopping time of a single car? Is this because the cars themselves take a long time to stop, or ...
1
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2answers
107 views

Physics of a sprint start

I am looking for an explanation to this illustration of a sprinter coming out of the blocks: Apparently, the production of horizontal force produces a great deal of body rotation (R1) which would ...