Questions tagged [newtonian-mechanics]

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 concepts, use [classical-mechanics]. For Newton’s description of gravity, use [newtonian-gravity].

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How to find the maximum angular speed of the bob of a simple pendulum?

This is the math: We are concerned with 'c' My attempt: According to the law of conservation of energy, the total energy of the bob at A & B will be equal. Now, at A, the total energy is just the ...
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The another answer for a question

The standard answer for this question is $\frac{2mgh}{(h-L)^2}$ and this is derived from conservation of energy. However, is there another answer to this problem? Since Kate just touches the surface ...
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Oblique collisions

I have learnt that the COM moves in a straight line an elastic collision of 2 discs. My question is Can I use this fact for solving collision problems rather than using Conservation of linear momentum?...
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Minimum braking distance

Suppose we are biking at a constant speed, is the minimum braking distance the same whether we apply the brakes on the front wheel or the back wheel? I admit this is a homework problem, but I can't ...
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Question on Angular momentum due in non-inertial system?

A smooth horizontal disc with a constant angular velocity $\omega$ about a stationary vertical axis passing through its centre, the point O. At a moment $t=0$ a mass is set in motion from that point ...
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How to use Centrifugal force in a rotating frame?

Assume a stationary object (point object) on a smooth very large disc at a distance $r$ from its axis perpendicular and passing through the centre. (No external forces apart from gravity and Normal ...
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Find position of a particle with respect to inertial frame S

The position of point in frame S' moving with a constant velocity of 10 ms along X-direction is given as (11,9, 8). Find its position with respect to frame S if their origins coincided second later.
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How do I know from free body diagram is object moving or at rest?

Object at rest or object that is moving with constant speed has same free body diagram (FBD). How do I know looking only at FBD is object moving or at rest?
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The Newton's third law and spring [duplicate]

According to the picture above,when the restoring force pull the block, the block is also stretching the spring , so the spring should not restore. Well I am totally confused with this question . Help ...
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Inside an O'Neill cylinder, would a Pendulum's swing have any notable characteristics?

Objects inside an O'Neill Cylinder would feel the Centrifugal effect, given by: $F=mω^2r$, and the Coriolis effect, given by: $F=d(mv)/dt$, as well as air friction from air under the same effects. At ...
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Torque problem solving question

I understand torque is a vector and thus has both a magnitude and direction and that we normally set CCW rotation as positive and vice versa but for a lot of the problems I do, I see the sign in front ...
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What impact does air have on our weight?

Although air is light, it is fluid. So it must exert upthrust on people. So does it mean, in fact, we are heavier than our weight? Also, the gravitational acceleration is bigger than its value?
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Why does the equation for time period of a simple pendulum become less accurate at angular displacements greater than 20 degrees? [duplicate]

I am currently writing up a practical involving a simple pendulum and changing the weight of a fixed length to see how that affects the time period. This can be defined using the equation: $t = 2\pi \...
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Dropping an anvil on a see-saw

Consider a see-saw/lever with pivot point at the middle and with a $200$ $kg$ anvil $A$ on one end. Suppose I drop a $100$ $kg$ anvil $B$ on the other end. The main question is, what would happen? Let'...
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Which forces are stoping a moving bicycle?

So let's say a bicycle is moving at a constant speed velocity v. And now I apply the brakes, which causes the, say, the front wheel here, to rotate slower, which then in a way makes the friction force ...
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1answer
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Where does the energy go? [duplicate]

Suppose a typical case of a girl dancing and after sometime changing her $I$ (moment of inertia to rotate) faster, my doubt is in this case there is a non-zero difference in initial and final total KE ...
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Finding the current in the falling circular metal plate at any time $T$. (Magnetic field and Electricity) [closed]

A circular metal plate starts falling from rest, straight vertically in region of uniform magnetic field of intensity $B$. The magnetic field is parallel to the surface of earth and to the plane of ...
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4answers
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Issues carrying out Taylor Expansion for small oscillations

I have an equation of motion for a pendulum: $\ddot{\theta}+\frac{g}{l}\sin(\theta)-\dot{\phi}^2\sin(\theta)\cos(\theta)=0$ I want to taylor expand this equation for small oscillations, i.e.: $\theta =...
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How to determine acceleration of $m_2$ if the system is configured as follow? [closed]

The question is "Consider the system in the Figure above. Determine the acceleration of the mass $m_2$ if its mass is $n$ times greater than mass $m_1$ . Neglect the friction and masses of the ...
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Irodov 1.146 precission

Shouldn't we take centrifugal force by net $w$ which is about instantaneous axis of rotation? Solutions I saw said to take the precission frequency only which I am not able to understand, why?
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1answer
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Friction between two bodys ( on top of each other ) - finding acceleration [closed]

Okay, I have a question. Lets say the $Fs_{max}$ is 50N. And I want to find the acceleration of the two bodys. Untill it was $50N$, they were connected. but now, the Force is $55N$ ( pushed to the ...
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Estimate the eccentricity of the Earth's orbit using equinoxes

I was reading the wikipedia article on Kepler's laws (https://en.wikipedia.org/wiki/Kepler%27s_laws_of_planetary_motion) and I came across the following. "The eccentricity of the orbit of the ...
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1answer
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Walking pace and torque

How to understand the relationship between the mass of a person, the length of the legs and the walking pace? My professor tried to explain it but I didn't quite get it. So we can consider the hips as ...
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1answer
64 views

Fluid in beaker on inclined plane

On an inclined plane there is a beaker filled with fluid, what will be the shape of fluid as the beaker accelerates down? What I think is that the beaker accelerates with $g \sin\theta$ acceleration ...
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1answer
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Shadow Time for a Satellite on an Inclined Orbit

I am trying to calculate the shadow time for a satellite on an orbit that is inclined by some positive amount of degrees. I am able to calculate it for a non inlined orbit but i do not know how to go ...
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6answers
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Is Newton's 3rd law of motion not applicable to gravitational force?

Newton's law of gravitation states: Every particle attracts every other particle in the universe with a force that is directly proportional to the product of their masses and inversely proportional ...
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Why aren't jet engines used in cars? [closed]

From my "research", I found that there have been efforts to make cars with jet engines in them (mainly race cars), but all of them relied on the thrust produced by the jet engine. Why can't ...
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Why is the concept of torque necessary?

In my physics textbook (“Physics for Scientists and Engineers” by Serway and Jewett) it says that “the cause of changes in the rotational motion of an object about some axis is measured by a quantity ...
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1answer
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Elastic collision of a ball against a container wall

I am writing a python script which calculates the final velocity of a ball after colliding with the wall of the container. The entire system is in 2D. The collisions are elastic, and the balls are all ...
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51 views

Doesn't the assumption of equilibrium make this answer wrong as a proof of the law of the lever?

This answer was written to the question 'Proof of the Law of the Lever'. I think it is wrong because it assumes that the system is in equilibrium without logical proof. If we set the configuration as ...
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1answer
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How to relate Laplace-Runge-Lenz vector to eccentricity?

So the eccentricity can be written in this form but I cannot find a proof or figure it out on my own.
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1answer
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Why conservation of energy does not apply in this case?

A disk, with rotational inertia $J$, rotates with angular velocity $w_0$ around a vertical axis, which has negligible rotational inertia. A second disk, initially at rest and with $2J$ inertia, is ...
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Rope tension in pulley system [closed]

I would like some help with a quick question regarding the below diagram [![pulley][1]][1] In this picture a 1t load is being lifted by a winch capable of lifting 3t The rope mass is 100kg and the ...
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3answers
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Why the velocity vector is perpendicular to the position vector in a circular motion?

I know by definition it should be perpendicular I just don't get why
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Analytic solutions for the (large oscillations) simple, variable frequency pendulum [closed]

This is a cross-post, It is well known that if we allow for large oscillations the equation for a simple pendulum, $$ \begin{equation*} \frac{\mathrm{d}^2\theta(t)}{\mathrm{d}t^2}=-\omega^2\sin\theta(...
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Can you calculate kinetic energy with the rocket equation?

Is it possible to calculate kinetic energy with the rocket equation? I am doing a quick school project on the efficiency of a rocket. What if we write velocity with the kinetic energy formula. $E_k=\...
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Bungee jump energy conservation [closed]

Problem A person with mass $M$ jumps from a bridge and performs a bungee jump. At the lowest point, the rope's length is $L_2 = 56 \, \textrm{m}$. The person oscillates for a while until the velocity ...
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Potential Energy surface with Spring and Gravity: Bouncing Ball on a Spring [closed]

Can someone provide clues to approaching each of these sub-questions?
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Problem of impulse [closed]

Can someone explain which formular I need to use for each questions in this problem?(a,b,c,d) During a game of miniature billiards with their friends, they hit the white ball (1, Radius r = 9 mm) on ...
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1answer
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How can I accelerate the linear speed of a spinning rock on a string when the rope can exert no net torque on the rock?

If I take a rock attached to a mass-less rope and start spinning it over my head (or on a friction-less surface, I don't think it matters) I can accelerate the linear speed of the rock (I can spin it ...
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4answers
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For a spacecraft orbiting a planet, orbital speed is inversely proportional to orbit radius. But speed must be increased to increase orbit radius?

For a spacecraft in orbit with radius $r$ with speed $v$ around a planet, centripetal force $F_C$ is provided by gravity: $$\frac{GmM}{r^2}=\frac{mv^2}{r},$$ which simplifies to $$\frac{GM}{r}=v^2.$$ ...
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Young's Modulus as a function of temperature

Is there a formula that relates Young's Modulus as a function of temperature? From Wikipedia, there is this formula in section 3.3: https://en.wikipedia.org/wiki/Young%27s_modulus I tried my best to ...
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1answer
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What is the relationship between velocity and time of an object gliding through water?

I took a video of a swimmer pushing off of the wall and gliding through the water until they come to a stop. Using some video analysis software, I was able to plot data points for their velocity over ...
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1answer
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Finding the angle that gives longest path for projectile motion using the average speed over the vertical displacement of object

For projectile motion, let's say a ball is launched at an angle a with respect to the horizontal, upwards. If I want to find an expression for the length of the path travelled by the ball before it ...
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1answer
48 views

How one derives this formula? [closed]

Recently I have seen the following formula for motion of rigid body with a fixed point: $$\dfrac{dT}{dt}=\int\limits_{0}^{t}M_{O}(\tau)d\tau$$ and I have no clue how this formula is derived. Could you ...
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What shape must a bowl be to have a ball rolling in the bowl execute perfect simple harmonic motion?

If we imagine a 2d semisphere "bowl" with a ball resting at the bottom. The ball can be slightly displaced and will roll back and forth crossing the bottom of the bowl an infinite number of ...
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1answer
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How do you calculate X and Y forces for this static equilibrium question? [closed]

I was solving a static equilibrium question, in which they said that, there is a $1$ m long uniform beam that is balanced, as shown in the below image. They asked what will forces X and Y equal? ...
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1answer
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What is the reaction force to the spring force?

Suppose we have a spring suspended downwards and a mass of block M that is pulling that spring downwards. We have the W force (that is m x g) acting upon that mass of block M and we have the spring ...
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Motion of a body present in a satellite

Question1- while writing the total enerygy of a body in a satellite revolving around a planet,does kinetic energy of the body also have to be included ? If not,why? Question2-when the above body is ...
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2answers
70 views

Solving this problem using the Work-Energy Theorem [closed]

A block is tied to a string wound on a cylinder of mass $m$ and radius $r$, (Through a pulley) which can rotate about its axis on a massless mount placed on a smooth surface. The system is released ...

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