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 discussion of energy, momentum conservation etc., use classical-mechanics, for Newton’s description of gravity, use newtonian-gravity.

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Work of a fixed wall

In this link here, What work is done by the wall when a ball hits it? The answer to the question if a wall performs work when hit by a ball was, that the wall does no work if it isn't displaced. But ...
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What's the relationship between velocity components in the Coriolis effect

I still haven't understood why Coriolis parameter in $(x,y,z)$ plane has its velocity components described as follows: $$\frac{du}{dt} = f\cdot v$$ and $$\frac{dv}{dt} = -f\cdot u$$ Why does the ...
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How to calculate the frictional force required to “stick” two rotating objects?

Say you had two fixed, non-identical objects rotating around one axis at different speeds relative to one another, and they can be coupled together by friction (like how a clutch in a car works). How ...
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Deriving the dynamic friction of an oversize shaft in a hole

I want to derive the force of dynamic friction of an oversized shaft in a hole. Suppose the dynamic coefficient of friction is $\mu$. Here is my attempt. Suppose the hole has diameter $d$ and the ...
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Work done on object in space

Suppose we apply a force of 1N on an object in space,due to Newton's 1st law of motion it should go on forever,therefore it's displacement goes on increasing.Does that mean that work done is infinite,...
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Intermediate axis theorem in higher dimensions

The intermediate axis theorem states that the rotation of an object around its first and third principal axes is stable, while rotation around its second principal axis (or intermediate axis) is not. ...
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Why don't we always lift stuff from center (center of mass)?

if you lift a large box alone, you try to lift it from the Center(Center of mass),but if the box is small you just use both of your hands each grabbing a side of the box(not from center of mass). if ...
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3answers
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What will be the force when you push a wall?

force is change in velocity times mass so if i push a wall there will be no change in velocity of the wall it will be in rest,acceralation will be 0, and so the force should be zero.So it means that ...
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Work done by friction in a complicated path [closed]

A block of mass $M$ is taken from point $A$ to point $B$ in a complex path by a force $F$ which is always tangential to the path. We also have coefficient of friction as $K$. What will be the work ...
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Reaction Force or Normal Force? [duplicate]

When we punch a wall our hand hurts... Do we feel the pain due to the normal force exerted by the wall or due to the reaction force?
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Why is the angular acceleration of a DC motor different according to the rotation direction in the same voltage?

I experimented with a DC motor to measure an angle, angular velocity and angular acceleration. The angular acceleration was differently measured according to the rotation direction, even though the ...
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Two-coupled oscillator: Doubt in finding normal modes and natural frequency

I want to find the natural frequency of a two coupled oscillator system like this- My book does it this way but I don't really get it. The equations of motion for the pendula are- $$I\frac{d^...
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Why does the phase velocity of a string attached to springs depend on the wave length?

A string can be described by the wave equation $$ (\partial_t^2 - \partial_x^2) \, \varphi = 0 $$ while a string attached to a spring (i.e. with a harmonic restoring force) at each location is ...
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Tension within a hypothetical pulley system

The following hypothetical pulley system exists: A massless rope passes over a frictionless pulley. Particles of mass M and M+m are suspended from the two differents ends of the rope. If m=0, the ...
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Power in different reference frames

I would like to reopen the question asked in this post because I am not quite satisfied with the accepted answer. Imagine observer A stationary (in world reference frame) and observer B moving with ...
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If an object falling at terminal velocity is pushed sideways, does it slow down vertically?

For reference, I'm using this equation for drag $$d = c \times {\rho \times v^2 \over 2} \times a$$ And this one for finding terminal velocity $$v = \sqrt{2 \times m \times g \over \rho \times a \...
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Kinetic Energy in a non-inertial frame

This is the question I was solving: A ball of mass m is released from A inside a smooth wedge of mass m as shown in figure. What is the speed of the wedge when the ball reaches point B? This was ...
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How do I find which end of the see-saw is either heavier or equal when the weight on the lever sits at different locations?

How do I find which end of the see-saw is either heavier or equal when the weight on the lever sits at different locations? In this photo each line throughout the lever represents 1 ft and whichever ...
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Wouldn't everything behave as a non-rigid body if action and reaction were not simultaneous? [closed]

If action and reaction would occur after some delay (basically,they were not simultaneous), would the consequence be that everything in universe would pass through each other? As an example If I try ...
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Is the Olympic running race fair? [closed]

I noticed that the 200-meter sprints are conducted on curved tracks. (See this video: world championship semifinals 2009) Isn't that weird? I mean, just look at the curvatures of each lane! (Source)...
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1answer
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Particle sliding on a sphere with friction

This is a generalization of the question Particle sliding on a sphere when we also have friction given by $F_f = \mu N$. See the following figure: Before doing anything, we can imagine what friction ...
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How can we know direction of blocks in pulley systems?

How can we find the direction of acceleration in pulley systems so that we can write equation of motion for different parts of the pulley system. Do we have to assume acceleration in some particular ...
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Is the centre of charge always within the centre of mass of an object?

What I am confused about is whether the charge of an object is concentrated within the centre of the mass itself, or does it change depending on the situation?
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Impulse on a pivoted rod holding two point masses on its ends

So, I'm studying for an entrance exam and came across this question. We hit the bottom block of mass $M=2.5 kg$ with a hammer. This block is attached to a massless rod of length $\ell=0.6m$, pivoted ...
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Pressurized gas through a poppet valve

I have a question and I have been unable to find an answer online. I'm wondering how it is possible to calculate the amount of $\mathrm{CO}_2$ and at what pressure that $\mathrm{CO}_2$ will be at as ...
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How should the spring constant of a cord scale with uniform changes in its overall size? (length and diameter)

Stemming from this: if a girl is playing with a paddle ball, and the toy and her are suddenly shrunk to a size 100 times smaller in all three dimensions, how will this change of scale affect the ...
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Angular acceleration in respect of speed, radius and rotations [closed]

I have a physics problem that I can't solve. The problem goes as follows: An objects spins around a point (radius $r$) $n-$times. After that the object is released at a given speed ($v$). The ...
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Why when change in kinetic energy equals to zero the work done by two opposite forces is equal even if displacement takes place?

For example if we pull a block on an incline. Then the force of gravity i.e. $mg \sin(θ)$ will be equal to force applied so that the net work done will be zero. But if $mg \sin(θ)$ is equal to force ...
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What concept describes a force acting on the edge of an object

Consider the following scenario: When studying forces, we know that when there is an unbalanced force acting on an object (let's say a textbook), the textbook moves in the direction of the unbalanced ...
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How can you predict whether an object is going to rotate? (question about torque)

I know a torque causes angular acceleration, but the derivation for the formula $\tau = I \alpha$ seems to assume the object is going to rotate in the first place, as it uses the identity $a_{tan} = R ...
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Are application of external force and origin of friction not simultaneous events?

A famous kindergarten school experiment "The snatching cardboard and friction" intrigued me to ask this question. Consider an empty glass placed on a table.Put a plane cardboard over the glass and ...
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Why is the force not included?

I'm reading my physics book trying to understand how to create force equations. (This next test is going to be a flop.) In this example, it states that if we were trying to find the tension in the ...
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Can I explain lift in this way?

** As shown above, Suppose the wing moves horizontally.** The red arrow is the direction of air movement at the top of the wing. This direction is not perpendicular to the normal line at the top of ...
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What determines the top speed in ice skating?

I was watching a hockey skating competition. The best skaters are able to accelerate quickly and turn without losing much speed; however, most people have similar top speed around 20-25 mph. What is ...
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Why do far sound getting sometime louder and sometime fainter?

Actually I was walking on my roof and have heard some kind song coming from far distant loud speaker. Which getting louder sometime(sometime air blowing to me at that instant) and sometime getting ...
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Rotational dynamics problem [closed]

I have a hard time solving this problem, going a right way about setting up the equations. What are the properties one could use in this setting to solve for the speed of change of the Radius of the ...
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Principles of Physics book question [closed]

A small block of mass m is sent sliding with velocity v along a slab of mass 10m, starting at a distance of l from the far end of the slab. The coefficient of kinetic friction between the slab and the ...
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What if we apply a force to stop object on a frictionless surface?

A force is exerted on an object for an instant. Will the object constantly accelerate, or will it gain a fixed velocity?
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Doubt in cylinder going up a step at constant angular speed

I have this problem here: I think I know how to solve everything except for the number 2). I studied in the mechanics subject that $W_{ext}=K_{2}-K_{1}$. Where $W_{ext}$ is the external forces' work ...
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Proof for condition of a Force being conservative

While studying Mechanics, I came to know about a way to test whether a force is conservative. Check whether the expression for the Work done is solvable without the path of the object that is $\int \...
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Intuitive understanding of angular momentum in cartesian coordinates

If a point-mass body is moving in a plane $z=0$, its angular momentum can be taken to be a scalar, and from the vector product formulas (assuming $m=1$ as I'm only interested in geometry), its value ...
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Will there be buoyancy in a space with atmospheric pressure and no gravity?

If there is pressure but not gravity will there be buoyancy? For example on an inertial spacecraft. I guess there will be no buoyancy, because there will be no direction of buoyancy without gravity.
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Kinetic Energy of a spring cylinder system

Consider the system in the above diagram. The surface has enough friction to initiate pure rolling. Questions: 1)If we stretch the spring from the equilibrium by about some distance x. The spring ...
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Successive amplitudes in quantum mechanics

In quantum mechanics we define amplitudes for events, like propagation from one point to some other point. Lets say that from a source to detector we have some amplitude (D/S). But, lets now say that ...
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Dynamics problem related to harmonic motion

I am unable to proceed further , the particle in this is falling with variable acceleration Fy toward origin with its greatest and least values given of the function is given, please explain where ...
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Questin on Motion in Gravitational Field

I just feel like I don't fully understand the following multiple-choice question despite the fact that I got the answer (which I still don't know if it's correct or not). "An astronaut is standing ...
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Where is the momentum going?

When a ball of mass $m$ collides elastically having velocity $v$ with a wall, then it retraces itself with the same velocity. Impulse on the ball due to wall is $2mv$ and since there is no external ...
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Rolling ball while winding a tape [closed]

I've been trying to solve this for a hours but i can't build the equations related problem involving this question, could someone help me? a ball of mass $m$ and radius $r$ rolls down without sliding ...
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2answers
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Creating a Gravitational 2-body simulation

I am trying to create a simulation for a gravitational 2 body problem. But I am kind of having trouble to define the equations that can be solve numerically. From an inertial frame I defined the ...
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Does a friction force act on a body on a flat surface with no external force?

I know that if an object is on an incline, there is friction as a reaction to the component of the object's mass that is parallel to the surface. I know that if an object is on a flat surface and an ...