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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44 views

Doppler effect with circular motion [closed]

I've been struggling with this question that turned up in a physics exam last year and just can seem to get anywhere close to the answer. From the attached picture: An object is moving in a circle ...
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1answer
32 views

What does a scale attached to an Atwood machine measure?

Assuming a massless and frictionless pulley with two arbitrary masses, what is it that the scale actually measures of the system?
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1answer
40 views

Circular Motion Question - 11th Grade

I have been recently solving physics questions since I have an exam next week. I came up across the following question and I have been trying for a good amount of hours to solve this question. The ...
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1answer
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Variation of Intrinsic losses w.r.t spring constant

How intrinsic friction losses (or energy losses) of a real spring varies w.r.t its spring constant? I am not expecting a direct relationship between the two, but at least whether more stiffer springs ...
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Mass calculation of a body having a constant horizontal force of 10 N which travels 18 m in 6 seconds? [closed]

How i must calculate mass of a body having a constant horizontal force of 10 N which travels 18 m in 6 seconds? I had thought of finding acceleration in order to apply the second law of dynamics, but ...
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1answer
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Pulley problem: I included the here the the picture of what i already tried doing [closed]

Pulley problem Problem: Find the tensions in the two cords and the acceleration of the blocks if friction is negligible. The pulleys are massless and frictionless, m1=200g, m2=500g and m3=400g. I am ...
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4answers
78 views

When to use $x = A \sin (wt + p)$ and $x = A \cos (wt+p)$ during Simple Harmonic motion when we start our clock not between mean and extreme position? [duplicate]

When to use $x = A \sin (wt + p)$ and $x = A \cos (wt+p)$ during Simple Harmonic motion when we start our clock when the object is between mean position and extreme position ? I have been trying to ...
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4answers
120 views

Partial derivative in Newtons Second law

Newton's second law states Force is the time derivative of momentum. But is it a total derivative or partial derivative? What is the reason behind it?
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How to find angle using $τ = Iα$? [closed]

I want to find angle (radians) using the formula: $τ = Iα$ . I guess after finding angular acceleration α I have to do an integration but I am not sure which method I should use.
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1answer
65 views

Why does the left cup’s top region till where the water is filled the most hot point and not the points below?

So I have two cups here. Black cup on the left and a white cup on the right.The region where I have made a dark red horizontal line is the region till where the water is filled.The left one is made ...
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Explain briefly why the total mechanical energy is not conserved

A uniform circular disk is free to rotate in a vertical plane about a smooth horizontal axis through its center $O$. An insect P is at the lowest point A of the disk and the whole system is at rest. ...
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Computing the distance where two solids reach each other using basic speed formula (high school problem) [closed]

A car$B$ which moves in a straight line at a speed of $50km/h$ arrives at a point$B$ ($d_{B}$) on the line, and a car $A$ which moves in the same straight line at a speed of $100km/h$ reach the point$...
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1answer
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Why collisions with other molecules not taken in account here?

I have few doubts related to this derivation why collisions with other molecules not taken into account since they could also influence the time it takes for one molecule to collide with the wall how ...
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3answers
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Rotational Equilibrium of a Rotating Titled Rod about a Vertical Axis

Consider: Here a rod AB is rotating about a vertical axis with a constant angular velocity and is supposed to not fall down but maintain its angle with the vertical axis. Here the point of suspension ...
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17 views

Calculation of Intrinsic energy losses of spring

How can I calculate intrinsic damping energy losses of a spring theoretically. What variables do I need in order to get an approx idea of internal energy losses of spring?
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3answers
56 views

What drives the free end of a slackened string?

Let's consider a gentle situation. A small puck is attached to a string. The string is sufficiently long in length. The setup is placed on a frictionless surface. One end of the string is nailed to ...
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1answer
33 views

Energy lost due to air drag of a varying velocity object [closed]

How do we calculate total energy lost of an object due to air drag which is moving with varying velocity (from $v_1$ to $v_2$ m/s with an acceleration $a$ and over a displacement $s$) in air? Assume ...
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Where have I made a mistake (momentum calculation vs kinetic energy calculation)? [closed]

Here is the problem: Sleds of mass $m_1 = 2kg$ are sliding on the ice with speed of $v_1 = 6m/s$. A package of mass $m_2 = 10kg$ was placed on them. Calculate the speed of the sleds after placing the ...
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53 views

What happens to their momentum? [closed]

A Russian cosmonaut with mass 87 kg and a US astronaut with mass 94 kg are outside the ISS and decide to run a momentum experiment. They are motionless facing each other palm to palm, then push apart ...
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2answers
54 views

What is the derivative of velocity with respect to height?

I have a question on fluid dynamics which requires to find the derivative of velocity wrt to height? It was solved by my teacher but I am not able to grasp the solution. Here is the question: - A tank ...
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1answer
24 views

Why does the bottommost point of a rolling body have a radial acceleration in the ground frame?

Let's say a solid cylinder of radius r is rolling on a stationary horizontal surface with linear velocity v, angular velocity $\omega$, linear acceleration a and angular acceleration $\alpha$ Bottom ...
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2answers
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What is the physical significance of the rate of change of a body's momentum with respect to the displacement it travels through, $dp/dx$?

This is something I've been trying to wrap my head around as I review mechanics, particularly conservation laws, in depth. I see the conservation of momentum and conservation of energy as sort of two ...
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Is there a way to solve this question using instantaneous center method? [closed]

This question is about instantaneous center method of finding velocities. I saw this question on a exam paper, but i think the question may be wrong because i couldn't find a way to get IC(1,3) Or ...
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2answers
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What is direction of tension at the extrema end of the pulley which it curves around?

Following from this answer, we see that tension switches direction after we cross the top most point of the pulley. Ok, so this is fine that tension points in opposite direction (horizontally) after ...
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38 views

Find the tangential velocity and angle when the object slips of the sphere [closed]

An object is located in the highest point of a sphere with a radius of 0.5 meters. After given a little push, it starts going down. a) Find the tangential velocity at the point where the object loses ...
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Mechanics accleration question and kinetic energy

I am really confused by this and I don't know why: Take the Earth to be spinning at 100,000 m/s at the surface. If I throw a ball on earth at 1m/s then its true velocity is 100,001 m/s Therefore, ...
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Moment on a rectangular concrete slab

Here is a picture from my engineering textbook. It describes a concrete slab being subjected to normal force $P$ and a certain moment. The moment is expressed by the normal load $P$ affecting at some ...
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2answers
41 views

Kinetic energy and acceleration of two bodies (easy) [closed]

I am really confused by this and I am not sure what assumption I have made that is wrong. KE $ = \frac{1}{2}m v^2 $. Consider a system of a BOX and a BALL and they both have a mass of $2 kg$ each: ...
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Calculating the direction of friction on an inclined plane/Determining the fate of a round body on an inclined plane

Question: If a round object (say ring or a sphere) is kept on a rough inclined plane of inclination $\theta$ and coefficient of friction $\mu$ is such that it exactly balances the component of weight ...
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1answer
37 views

Body falling off a smooth hemisphere - simple but I'm missing something. What is it?

So here's the question that I'm stuck on. A particle slides from the top of a smooth hemispherical surface of radius $R$ which is fixed on a horizontal surface. If it separates from the hemisphere at ...
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Jerk problem, race car weight transfer

If there is a mass with 1G force in one direction and a opposing linear changing force from 0 at the start to a equal force to the 1G when motion stops. The only other info known is a displacement of ....
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1answer
57 views

What is wrong with the student's free body diagram? [closed]

Spent an entire class period going over this and teacher just laughed at us and refused to guide us in the right direction. We
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1answer
57 views

Are the following two situations equivalent?

Below are the two different situations in which the rope wraps twice around the top of the top pulley and bottom of the bottom pulley(Assume that the segment of the rope attached to the center of top ...
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7answers
216 views

Feeling heavy in an upward accelerating elevator - is it a pseudo force?

In an elevator accelerating upwards, a person weighs "heavier" on a scale. The normal force can be expressed as $N=m(a+g)$, a being the upward acceleration. In this case, is $ma$ a fictional ...
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1answer
26 views

Is centripetal acceleration an inertial acceleration?

I am trying to understand what component of the force on an object moving in a regular bowl enables the ball to complete a "semi circle", without any external force being applied. Is the net ...
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1answer
33 views

What is meant by “pseudo forces are mathematical corrections in non-inertial frames”? [closed]

I have read in several posts that "pseudo forces are mathematical corrections in non-inertial frames" that enable Newton's second law to hold true. How is this "correction" related ...
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1answer
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Can someone please explain this paragraph on work from the Feynman lectures?

This is a portion from Feynman Lectures: ...............We have proved previously that the answer is zero for any path composed of a series of notches like those of Fig. 13–3, and also that we do the ...
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1answer
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Finding the maximum force acting on a rolling tire

I have a problem where a lone tire is rolling, we may assume that the tire is a uniform disk. I need to find the maximum force acting on the tire as a function of friction if the tire rolls without ...
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2answers
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Calculate total angular momentum of object rotating about 2 axis (e.g. Earth)

Consider the Earth. It rotates about its own axis (going through the poles) with some angular velocity $\vec\omega$, and around the sun, with some angular velocity $\vec\Omega$. In every textbook/web ...
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2answers
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Are mass and force defined simultaneously? [duplicate]

Everything I am talking about here takes place in the Newtonian mechanics, but it is also interesting to discuss everything in the context of special theory of relativity, quantum-mechanics or even ...
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2answers
62 views

Force analysis in a compound pulley system

At 4:56 of this video on compound pulley systems with the following schematic set up: The professor does a force analysis of the forces on the pulley A , and strangely (for me) , he finds that there ...
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1answer
51 views

Circular motion problem - is this solution correct?

Recently in my physics class, my instructor introduced this problem, yet I have some doubts about how to answer the question, as I believe it is missing some information. I have thought about the ...
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1answer
71 views

Why is the $\frac{1}{2}$ significant in $\frac{1}{2}\rho v^2 C_d A$? [duplicate]

The formula for drag force is $F_D=\frac{1}{2}\rho v^2 C_d A$. Why is the $\frac{1}{2}$ significant here? I think that the drag coefficient $C_d$ already serves the purpose. Is it for a historical ...
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1answer
48 views

How to calculate moment of inertia double rotation?

How to calculate moment of ineria of disk if it has double rotation, shown on picture below.
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1answer
45 views

Proof of work-energy theorem for a rigid body

Could anyone show me a way to derive the work energy theorem for a rigid body whose motion is along a fixed axis ( such as of a cylinder rolling on a plane) which states that states that $W=\frac{1}{2}...
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1answer
67 views

Which force exerted a torque?

Suppose a horizontal disc fixed in the center with a vertical shaft passing perpendicular to the plane, is rotating at some angular speed and there is an insect sitting initially at center. The insect ...
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3answers
58 views

Newton 3rd law confusion [duplicate]

Why do things even move? I mean based on Newton 3rd law no matter how much force you exert on an object, it will always exert an equal and opposite force back to you. So why do things move?
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1answer
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Disk rotating around centre and around another axis

Is it possible to calculate the moment of inertia of a disk that is rotating around its centre and simultaneously circling around another axis that is paralled to the one in the cente. For example... ...
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3answers
93 views

Why does normal force work?

I've got a lot of question about normal force. First, what causes normal force. Next, how do the object know how much normal force to exert. Lastly, how is this not an application of Newton 3rd law. ...
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2answers
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Is this correct regarding velocity of train?

So many yellow T drawn are just different position of train at different instants.The person is standing still at all those instants at one place. If a train is moving at 5m/s. Then for me , can we ...