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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How exactly is a normal force exerted, at the molecular level?

I've been surfing the web for quite a while, finding the answers I would need, but couldn't find a convincing one. First of all I need to remind you that this a very long/continuous question, so ...
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A bar weighs 2N and is 5m in length. What is the weight(M) needed to balance the bar? [on hold]

A bar weighs 2N and is 5m in length. What is the weight(M) needed to balance the bar? I think I understand that the equation not including the weight of the bar would have 3*3=(5*1)+(2*X) M=4. I don'...
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Acceleration in Circular motion

Can motion of a particle be circular if radial acceleration is zero but tangential acceleration is not 0?
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A catenary problem [on hold]

A uniform rope of length $L$ is suspended between two fixed nails A and B that are in the same horizontal level. If the Rope makes an angle $\theta$ with the horizontal at the nails, find depth h of ...
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Randomly stopped dynamics of $x(t)$: How can I find $\text{var}\{ x(t) \}$?

Consider the simple dynamical equation $$ \dot{x}(t) = u H(t-\tau),$$ where the timescale $\tau$ is an exponentially distributed random variable $\tau \sim \omega \exp\{\omega \tau\}$ and $H(t) = 1-\...
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1answer
68 views

What do you mean by Newtonian space? [on hold]

What do you mean by Newtonian space? When you see this question, most of you might be thinking that I am trying to crack a joke or something..but no. This was a genuine doubt which one of my friends ...
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Formula of Heat Generated by Continuous or Acute Force Exertion on Elastic Object

See the figure below. Ignoring friction but not elasticity, I am assuming the object will be deformed and heat up by part of the energy transferred by F. What does the general formula to demonstrate ...
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1answer
27 views

Analysis of motion of block attached to spring

A block is attached to a spring of constant k and natural length lo . One end of spring is fixed and block is given a velocity Vo. System is is horizontal plane. The maximum extension in spring is ...
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3answers
51 views

Z-shaped lever balance

The goal is to find out whether a Z-shaped lever will fall over due to gravity. See diagram below (sorry for MS Paint): The bottom edge $x$ is resting on a flat surface. All three edges, $x$, $y$, ...
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2answers
34 views

Finding Masses of Binary Star system w/o using Kepler's third law

I'm struggling with what feels like it should be a pretty straight-forward intro physics problem, but I'm missing something fundamental. The scenario is that there is a binary star system with two ...
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1answer
32 views

Net force explanation [on hold]

As we know, force = mass × acceleration. In the case of a body which doesn't move, like a big statue, even though I apply force, the force = zero, as we see a lot of force acting as to make it zero. ...
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3answers
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Magnitude of vector quantities

The gravitational force in the vector form is defined as $$ \vec{F}=-\frac{GMm}{\boldsymbol {r^3}}\vec{r}$$ Many textbooks define its magnitude as $$F_g=-\frac{GMm}{r^2}$$ However, in the derivation ...
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1answer
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How should the differential equation of a physical pendulum be written using clockwise rotation as positive?

Refer to figure $1$. Sticking to the convention (counterclockwise is positive) the differential equation for a physical pendulum is $$I\cdot D^2(θ) =-mgd\sin(θ)$$ since the torque of the gravity ...
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Force = Mass ⋅ Acceleration

I have a doubt on the formula, $$F=m\cdot a$$ In pushing the wall, as per formula, $F= m\cdot 0=0$ as there is no acceleration hence zero. Therefore force become zero. But we have applied some force ...
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1answer
178 views

Is the Galilean Cannon a demonstration of Newton's Third Law? How?

If it is, then how would one calculate the force acting upon each segment of the cannon. I was wondering if you could use F=ma to calculate the opposite reaction force the floor would exert to the ...
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Explanation on Newton's second law

I have asked a question on I pushing the wall,where the force of me is not zero but as per the formula F=m.a,the force is zero and then I got the answer , it is because here the net force is acting ...
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2answers
86 views

How the centripetal forces work on a point in a rigid body? [closed]

I know it was a question but when I asked last time I did not know the answer. It has been suggested that the question is not clear, it's badly written. Now I know the answer and I can introduce them ...
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1answer
13 views

Traslation of a bar on a plane - Contrasting results

I have a bar which can translate on a plane (gravity along y), at estremity A there are two forces and a moment, G is the center of mass, here I applied the gravity force: The dynamic equations are: ...
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1answer
34 views

Two black holes in rotation - Energy conservation

I was looking at this problem: Let consider two black holes of mass $M$ rotating around a point $O$ (circular montion). The first black hole center is $M_1$, the second $M_2$. Each of them has ...
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Effort to lift mast [on hold]

This information is for designing a sailboat mast raising system: The mast is of uniform weight for it's 25 foot length It is hinged (pinned) at one end. How do I determine the effort needed to ...
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1answer
147 views

Energy density and inernal density relations

If energy density relates to rest mass density as $\epsilon = \rho / c^2$. How internal energy relates to energy density? Also, when do we write $\epsilon = \rho / c^2$ an when $\epsilon = \rho / c ^2 ...
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5answers
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What determines the “strength of impact” of a falling object on the ground, momentum or energy?

I am considering free falling objects that eventually hit the ground. The objects have various masses and various final (ground-impact) velocities. What should I measure the "strength of impact" ...
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1answer
107 views

Is it correct for me to understand why air moves along a curved surface?

As shown in Fig. 1, water flows horizontally from A-A section, and it flows along the surface under the action of gravity. As long as the velocity is not high enough, the water will not leave the ...
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1answer
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How a stick can provide both normal force nad tension?

This is what I think. Please tell me, am I right?? If an external pulling force is applied on one end then there will be tension in opposite direction. And if an external pushing force is applied on ...
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3answers
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Is the velocity of the spinning rod constant after it's hit?

Say we've got a rod floating around in space, with two masses of $m_0$, one attached at each end. Let's say the rod has a length of $l$. There's another mass, $m_1$, moving at some velocity $v$ ...
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1answer
42 views

If we define downwards as the negative direction, can a falling object have positive acceleration?

In my textbook I have the following problem: A ball rolls along a table then falls off the edge landing on soft sand. Sketch the s–t, v–t, and a–t graphs for its vertical motion. The textbook's ...
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Kinetic Energy Formula [on hold]

I understand that the kinetic energy formula $\frac{1}{2}mv^2$ is the result of integrating momentum: $mv$ with respect to velocity $v$. That makes sense... ↑ mass = ↑ kinetic energy and ↑velocity = ↑...
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1answer
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Why ball fall at same location from where we throw it? [duplicate]

I have a silly question. As we all know earth is rotates at a speed of 460 m per sec. So if I throw a ball in the air for 10 sec than the ball must fall 4600 m away from me but these does not happen ...
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2answers
179 views

What is the relativistic Hamiltonian for a charged particle in an EM field, using the magnetic scalar potential?

The Hamiltonian for a relativistic charged particle moving in a static electromagnetic field is the well known: $$H=c\sqrt{\left(\mathbf{P}-q\mathbf{A}\right)^{2}+m^{2}c^{2}}+q\phi$$ where,\begin{...
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3answers
156 views

Why is the drag force proportional to $v^2$ and defined with a factor of $1/2$?

$$Drag = \frac{1}{2}C_d \rho Av^2$$ I understand that the strength of the drag depends on the density of the fluid the body passes through, the reference area of the body, the drag coefficient, and ...
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3answers
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Deriving SHM equation

i have derived SHM equation till here $$\sin\left( \frac{\sqrt k}{\sqrt m}\cdot t \right)$$ Now all the solutions (youtube and textbook) I'm looking are just stating intuitively $\frac{k}{m} = \text{...
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4answers
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How does Newton's 3rd Law apply to arm wrestling? [duplicate]

I understand that when we refer to Newton's third law, forces do not cancel out because action-reaction pair forces are acting on different objects. I tried to apply this to arm wrestling, but I am a ...
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1answer
71 views

In which direction does the impulse acts on ball when we throw it to ground? [on hold]

When we throw a ball to the ground then in which direction does the impulse acts on the ball?
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1answer
75 views

Cracking of pages

I have noticed that after using a book for some time, a few pages develop small cracks on them. What is the science behind it and can it really damage a book? Basically, something like this: And, if ...
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1answer
207 views

External forces in momentum conservation

I know that momentum conserves when no external forces interfere with a system. But I don’t completely understand it, here’s two examples that I don’t fully get: Two objects collide on a plane that ...
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0answers
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Pretension cable - Minimum Potential Energy Formulation [on hold]

If there is a geometry with pretension in an unstable state, like two cables with a predefined tension $T$ as seen in the figure. Due to a current geometry (which is not in equilibrium), there is an ...
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3answers
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Difficulty in understanding why a car slips towards outside as seen from inertial frame

While turning on a road, why does a car slip towards outside, if we are observing the car from inertial frame of reference, i.e center?
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3answers
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Why do the inner tyres of a vehicle rise when taking a turn at high speeds?

When a person cycles at high speed on a turn, his body bends inwards, to raise the horizontal component of the normal reaction to provide the centripetal force for the turn. The more the speed is, ...
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4answers
139 views

The physics of airplane flight

Physics in schools teaches two contradictory and mutually exclusive things: (1) That the upward lift force on an airplane in flight equal its weight (Lift = Weight = mass x gravity). This is based on ...
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1answer
288 views

Difference between yaw angle and slip angle

What's the difference between slip angle and yaw angle (speaking about cars)? It seems they both are the angle between the actual direction of travel and the direction towards which it is pointing.
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4answers
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Why does a car need more torque when accelerating from rest?

Since static friction helps in the movement of rolling motion, not opposes it, Why do we say we need more torque to get the car to move from rest if we have the rolling friction coefficient static ...
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2answers
148 views

Are springs compressed by energy, or by momentum?

An object is headed towards a spring at a constant velocity, no external force will act upon it, except for any force applied by the spring itself after the collision. Let's say the spring is of ...
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2answers
148 views

Why is torsional shear for a circular cross-section maximum at the biggest radius

Equation: Tao = (T*C)/J i know the equation but it just seems counter-intuitive that the maximum shear stress is at the biggest radius for 3 reasons that I have(thought of). 1- imagine/assume that ...
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1answer
29 views

Euler force for pendulum

Hello I have a question related to the Euler force. Why is this force never considered for a simple pendulum? As far as I understand, Euler force is given by (assume I would consider the 2d pendulum ...
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2answers
46 views

What are the necessary conditions for relative angular velocity to be defined?

I have certain doubts related to the definition of relative angular velocity .My textbook defines it in the manner given below:- $$\omega_{AB}=\frac{v_{AB}}{r_{AB}}$$ $\omega_{AB}$ is the relative ...
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1answer
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When a rod collides with a particle does the momentum of the centre of mass remain conserved or of the small part of rod colliding with the particle?

I have observed in many experiments on collisions involving rods of varying densities that the momentum seems to first be conserved only at the point of collision then about the centre of mass. Is my ...
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4answers
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Is Newton's third law really correct? [closed]

Suppose I am pushing a box on table with $10$ N force due to friction it is not moving and if i applied $20$ N the box started accelerating. Then, how does the box apply $20$ N force on me?Well ...
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0answers
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Toppling of a cylinder moving on a trolley [on hold]

A uniform $2$ kg cylinder rests on a trolley. The coefficient of static friction between the cylinder and trolley is $0.5$. If the cylinder is $4$ cm in diameter and $10$ cm in height, what is the ...
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1answer
45 views

Can you derive the Tsiolkovsky rocket equation without calculus?

Can you derive the Tsiolkovsky rocket equation without calculus?
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2answers
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Question about a crate in an accelerating truck and friction force

"A crate is sitting in the center of the back of a flatbed truck. As the truck accelerates to the east, the crate moves with it, not sliding on the bed of the truck. In what direction is the friction ...