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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Pushing a crate on a friction floor [on hold]

A man is pushing a crate at a constant velocity. there is a friction between the floor and the crate of $$\mu =0.41.$$ The pushing force is directed downward at an angle $\theta $ below the ...
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1answer
25 views

Displacement of an object due to opposite and equal forces acting at different times?

This question is about mechanical waves in solids, the speed at which forces propagate through solids, and the displacement that might occur due to unequal starting times of equally sized forces. ...
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1answer
32 views

Action Reaction Pairs and Work

Say that a ball is sitting in front of a compressed spring launcher. The spring is then released. The spring applies a force on the ball for a certain distance. This force is accompanied by an equal ...
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1answer
37 views

Work done by Internal Forces

Why is it that internal forces do not change the potential energy of the system? Assume that a man stands on earth with a dumbell. If the dumbell is the system, when it is raised a height h, the work ...
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16 views

Motion on inclined plane [on hold]

What is the entire mathematics of motion on inclined plane? I wish a thorough explanation of the behaviour like motion outside gravity field and inside it. In short why does an object on inclined ...
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3answers
98 views

Integral ambiguity

I'm a bit confused with some notation I encounter in physics calculus. Consider this: Taken from here. Integration operates on functions, correct? What does it mean to integrate $\frac{d{\bf ...
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1answer
53 views

Massive ropes and tension

Consider the diagram bellow, a massive string hanging in equilibrium My question is this: Can we take any 2 random point on the rope, say A and B and then use $\sum F=0$ on the rope between them: ...
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0answers
24 views

Find out angle of a projectile [on hold]

For a projectile launched from a point on horizontal ground, the speed when it is at the greatest height is 25−−√ times the speed when it is at half of its greatest height. Determine the angle of ...
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1answer
22 views

What is the work done below proportional to? [on hold]

A raindrop falls from a certain height to the ground, with a terminal velocity u. The viscous force is F = 6*3.14*n*r*v, where n is the coefficient of viscosity, r is the radius of the raindrop, and v ...
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0answers
24 views

Similarity in two events from Dynamics point of view [on hold]

What is similar from dynamic point of view between book lying stationary on horizontal table and rain drop falling down with constant speed? I can find two similarities Force acting on them is ...
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1answer
133 views

Why are D'Alembert's Principle and the Principle of Least Action Related?

Why do we get the same differential equations from both principles? Surely there is a fundamental connection between them? When written out, the two seem to have nothing in common. $$\sum _i ( ...
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2answers
27 views

Is centrifugal force equal in magnitude to the centripetal force in the frame of a body undergoing circular motion?

I was working out the minimum tangential velocity required for a swing to complete a full revolution and assumed the centripetal force is equal to the centrifugal force, so that I could set the weight ...
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2answers
29 views

Finding coefficient of friction between block and plane [on hold]

An inclined plane makes angle $\theta$ with horizontal. Upper half plane is perfectly smooth where as lower half is rough. The block of mass m starts sliding from top. If the block again comes to rest ...
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0answers
21 views

What is the angle of projection when at maximum height the speed of a projectile is half the speed at half the maximum height? [closed]

I have been struggling with this problem: The speed of a projectile when it reaches its maximum height is one half of its speed when it is at half its maximum height. What is the initial ...
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1answer
28 views

Modeling a stool with three legs pushed on one leg

If a stool with three legs is pushed (horizontally) on one leg in the direction of the axis passing through the other two legs, it starts both moving and rotating. Is it correct to assume 1/3 of ...
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1answer
57 views

Hooke's Law: why is only one force considered?

I have a question about Hooke's Law springs. What I learned is that a Hooke's Law spring gives a force F pushing left and right and each force equals $k \cdot |l-l_o|$ Let's say there is a mass ...
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7answers
378 views

Hit by two cars with same momentum but different mass. Which is more painful?

Suppose they have the same contact area with you. The term "painful" is a bit ambiguous. Let me ask in another way: Two cars with same momentum but different masses are going to hit a wall. You ...
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1answer
46 views

Reduced mass and harmonic mean

In two-body problems, a reduced mass has the form: $\frac{m_1 m_2}{m_1+m_2}$, which by appearance, is half of the harmonic mean of $m_1$ and $m_2$: ...
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1answer
42 views

Why is the range for a particle thrown at 90 degree same as that of a particle thrown at 0 degree? [duplicate]

There is a derivation given in my book which concludes to the fact that the range is same for two angles of projection, provided they are complementary. I fail to understand this fact. For example, ...
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1answer
43 views

Will A Vertical Projectile Travel the Same Distance as A Horizontal Projectile

If a projectile is fired vertically from an initial height, $h$, above ground level, and an identical projectile is fired with equal initial velocity from the same initial height in the horizontal ...
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1answer
66 views

Finding equilibrium of mechanical system

A system is described as follows: Consider a system consisting of two rotating bars of length $l$ and with uniform mass density and each with total mass $m$. The bars are attached to a common ...
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0answers
29 views

Find the relation between the displacements [closed]

Let there be a pulley moving downwards. It has mass $m_1$ to the left and $m_2$ to the right(latter has greater mass). Let in time interval $t$ , the pulley moves from $C$ to $C^`$ ; $m_1$ moves from ...
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2answers
1k views

Put a bullet into orbit around the moon

While I was watching this beautiful video, the absence of air friction pushed me to ask myself: While standing on the surface of the moon, what is the initial velocity by which you can fire a bullet ...
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1answer
65 views

How can I actually push heavier objects?

I've been thinking about Newton's third law lately because I couldn't understand a few things and I think I actually answered my own question. Could someone confirm if my reasoning is right or show me ...
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1answer
82 views

Moving wedge and pulley system

A wedge of mass $M$ rests on a rough horizontal surface with coefficient of static friction $\mu$. The face of the wedge is a smooth plane inclined at an angle $ \alpha$ to the horizontal. A mass ...
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1answer
29 views

Angular Momentum Conservation Definition [duplicate]

Did I missed something in angular momentum definition? Two identical bodies rotate around mass center. Now I invented anti-gravity and turning gravitational switch off. Those two bodies will move now ...
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0answers
36 views

How forces work during hammerthrow

I am not sure if I understand how forces work during hammerthrow. From my understanding athlete works with Fmuscle force on a ball and rotate it and a ball works with equal opposite force on an ...
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1answer
37 views

Distance along projectile motion [closed]

I was doing kinematics these days, projectile motion. And I did the basic concepts: range, max height, time of flight, projectile on inclined plane. I am curious to know how we would solve a question ...
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0answers
28 views

At what speed (km/h) are the ride-goers (harnessed at opposite ends of ends of “propeller”) travelling? [closed]

The Revelation is one of the fastest and most exhilarating extreme rides in the world! Designed like a giant airplane propeller, the Revelation holds two to four riders comfortably in the cockpit ...
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2answers
65 views

Does pulling or pushing take more effort? [duplicate]

In which case is more effort needed: when you push or when you pull? We have a common experience that man tends to first push anything. How it is justified and what are the reasons behind this?
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2answers
38 views

Free vs bound vectors and torque

When considering basic Newtonian mechanics, we can treat vector as free and move their point of application at will. This is consistent with the affine nature of Euclidean space. However, when ...
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0answers
16 views

Make an Electric motor work with help of 4 magnet wheels? [closed]

I am working on a car prototype that should work on the electricity that it generates with the help of magnets. The strong magnets will be fixed at the wheels. A Coil of thin copper wire(solenoid) ...
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1answer
47 views

Gravity and Mass

Two bodies of equal size and mass meet in space. My question is: will they attract each other equally or will their attraction cancel each other out?. Also: how long does it take for the two bodies ...
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1answer
48 views

What happens when the speed of a body is less than optimum speed?

Yesterday I learned about optimum speed. My teacher told that optimum speed is the speed with which one can take turns on banked road without wear and tear. $v_0=\sqrt{rg\tan\theta} $, $v_0$= ...
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1answer
30 views

How would we find what sort of a force this one is? [closed]

The potential energy for a force field is given by $U = -Kxy$, where $K$ is a constant. The body moves in an $x$-$y$ plane. Find the force vector. $i$ is the unit vector along the $x$ axis, $j$ is ...
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2answers
47 views

Find the minimum force that has to be applied to the block $m_1$ so that the other block just begins to slide

This is a problem from the book 'Problems in General Physics' by I E Irodov. Two blocks of masses $m_1$ and $m_2$ are placed on a rough horizontal surface, connected by a light spring. Find the ...
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1answer
93 views

When I move my arm forward in vacuum, will my body move backward?

Let's say I stay at point $x=0$ in vacuum. When I move my arm forward such that it will have a positive $x$ position (say $x=5$) will the rest of my body move backward such that it will have a ...
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1answer
62 views

How muscle force work? [closed]

If muscle works with force on joint and joint works with exact force on muscle(newton III law) how can muscle drag much heavier weight than itself?
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0answers
18 views

Inclined plane problem with friction [closed]

A block of mass 6.0 kg slides from rest at a height of 2.0 m down to a horizontal surface where it passes over a 1.5 m rough patch. After crossing this patch it climbs up another incline which is at ...
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1answer
50 views

Rational ratio of frequencies leads to isolating integral of motion

Padmanabhan's discussion of dynamics mentions that in general the two dimensional harmonic oscillator fills the surface of a two torus. He further notes that there will be an extra isolating integral ...
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0answers
21 views

Static Friction on a Circular Road [duplicate]

I was recently brushing up on my dynamics, when I saw the interpretation of how a car moves in a circular road. Apparently, the car can stay in a circle due to static friction acting inwards. But I ...
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0answers
32 views

Max speed as a function of engine power

My question started out as finding the maximum speed of a go kart, taking into account only the drag forces as force opposing the motor. I've done some investigation to find: $$ F_{drag}=\; ...
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0answers
33 views

A force applied to an inclined plane

Below are two drawn diagrams of the problem with some explanation. Note: I think my notation for the force that the block exerts on the plane in the horizontal direction is not the standard ...
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0answers
5 views

Why does every post here gets downvoted and disregarded? [migrated]

Why does every post here gets downvoted and disregarded, even though many users here are not even professional physicists? Much condescension and feeling of self value, for someone as partial, dont ...
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4answers
196 views

Does Newton's law and Quantum mechanics also apply for the matter which is not dead?

The following quote is extracted from the book "The Field-The quest for the secret force": ...There was other, quite practical, unfinished business with quantum theory. Bohr and his colleagues ...
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1answer
46 views

Equation of motion for a double pendulum

firstly I am a Grade 12 Physics student currently doing my final experimental investigation which I decided to do on double pendulums. Before I got into this, I was under the impression that there was ...
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3answers
3k views

How do crocodiles jump?

In a video (Here), I saw crocodiles jump vertically about three meters without using any solid surface. The wonderful thing is that when they start to jump, their vertical velocity is approximately ...
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0answers
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How to get rotation speed after disk-disk collision?

Assume two circular disks A and B collide. They have both initial linear momentum and angular momentum. If their surface has no friction, their angular velocity does not change after collision, so I ...
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1answer
40 views

Coupled Spring System (3 mass 3 springs)

Hello I am having trouble trying to find the correct model for this coupled spring system. The scenario is the following we have: Ceiling - Spring - Mass(1) - Spring(2) - Mass(2) - Spring (3) - ...
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1answer
46 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 ...