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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Phsyics Energy Problem + Concept

A simple problem really. Part 1 Suppose a ball ($20. ~kg$) was shot straight up with an initial velocity of $+50~m/s$. a. Assuming that all of the ball's initial $E_k$ was transformed into ...
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1answer
127 views

When dealing with pulleys and hanging masses, does one add or subtract tensions to find torque?

I'm very confused on this problem. A pulley has two hanging blocks on either side with one having a greater mass. To find the torque, do I have to add the tensions of both the blocks or subtract the ...
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3answers
45 views

Do I need to have a force acting in an opposite direction to feel the force of acceleration?

Suppose I'm in a rocket, accelerating away from the Earth. While I'm accelerating away from the Earth in the rocket, I can feel the force of acceleration. Now, let's suppose we take away the Earth, ...
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0answers
65 views

Precession of angular momentum vector

I'm studying Classical Mechanics on Goldstein's book, so I'm using his terminology and notation. First I'll explain where the question comes from: consider a heavy symmetrical top and consider the ...
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2answers
94 views

Why Earth is considered to be an inertial frame? [duplicate]

Earth rotates about its axis and also revolves around the Sun at the same time. So why Earth is considered as an inertial frame in Newtonian Physics. So technically, I'm effectively asking why the ...
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1answer
87 views

Newton Mechanics [closed]

I am confused about this question, what does it mean? A particle has a mass of $2\ \mathrm{kg}$ and a force $$F = 24t^2 i + ( 36t - 6 ) j - 12tk$$ acting on it. At the time $t = 0$ the particle is at ...
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2answers
76 views

Does friction depend on the direction of motion?

In my experiment of finding the moment of inertia of a flywheel, I first rotate the flywheel in the anticlockwise direction and then in the clockwise direction, but I am getting different values of ...
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0answers
17 views

Can we use the planets and Sun to fling out a craft at relativistic speeds? [duplicate]

E.g. The Voyager crafts took various assists from the planets. Sun being much more massive, wouldn't a spacecraft gain much more energy from such a flyby on the correct trajectory? If so then what ...
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1answer
41 views

Impact on landing with forward motion vs straight down

A skateboarder ollies down a set of stair. Is the impact when landing less than if dropped straight down from the same height?
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0answers
23 views

Momentum and Collision of a ball head on? [closed]

I'm stuck on a question with momentum and collision of two balls. Two balls move toward each other. Ball one is moving in the positive direction, has a mass of m1, and a velocity of v initially. ...
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0answers
39 views

A Four Spring-Mass Problem [closed]

Four rods(mass=m) are joined end to end to form a square such that each vertex is a hinge. This non rigid square frame is joined to four springs at each of its vertices such that each of them lies ...
3
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5answers
780 views

Why can't I push myself in a chair? [duplicate]

If I am sitting in a chair with wheels and someone pushes on the back of my chair with sufficient force it will role along the ground. However, if I push on the back of the chair with the same force ...
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0answers
42 views

Finding Tension of a fixed rod on a vertical wall [closed]

The question: A rod extends from a vertical wall at an angle of 27º from the horizontal. A 2.5-kg lamp is mounted at the end of the rod. After John throws his 300-g winter coat over the lamp, what ...
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3answers
104 views

Force exerted on carseats?

Can anyone explain how force is exerted on car seats during a crash? I am being told in car seat safety forums that $force=mass \times acceleration$. So if a $2000 \;\text{lb}$ vehicle bumps you at ...
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5answers
110 views

What is the proper vector form for the Gravity Formula?

We are familiar with the equation for calculating the velocity of an object in orbit given the central mass (or the mass given the orbital velocity): $$\frac{v^2}{r} = \frac{MG}{r^2}$$ I'm trying to ...
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0answers
14 views

Are the effects of faraday's law of induction worth considering in this experiment?

In my intro to physics lab at uni, we did an experiment where we were supposed to measure the amount of kinetic energy and momentum before and after collisions between two carts. For some reason, ...
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2answers
124 views

How to start an artificial gravity?

I understand how artificial gravity in space stations works. It is by normal force the wall exerts on the foot. But I wonder how to start it in the first place. I just learned about centrifugation ...
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1answer
24 views

If there is a non-slipping string pulling a cylindrical object, is the rotational acceleration the same as the translational acceleration?

The rotational velocity and translational velocity are the same right? Assuming the cylindrical object does not interact with anything other than the string which applies a force.
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0answers
352 views

Inertia of yo-yo goes to infinity, what is tension and acceleration?

For this part, imagine that the string is wound around the center axle of a yo-yo; the axle radius is Raxle, but the yo-yo casing has a radius Rcasing≫Raxle and moment of inertia I≫mr2axle. In the ...
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0answers
98 views

From Newton to Kepler without infinitesimals

I've read some interesting calculus-free proofs of at least parts of the derivation of Kepler's Laws from Newton's gravitational force. One is of course Feyman's "Lost Lecture" (which was already ...
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2answers
43 views

Finding the work done to fill the tank by pumping water over the edge? [closed]

I am really confused on how to approach the following question and how to set it up. So the question is: An open tank has the shape of a frustrum of a right circular cone. The tank is ...
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1answer
77 views

How much fuel do I need to send cubesat 1kg from Earth orbit to Moon orbit? [closed]

How much fuel do I need to send cubesat 1kg from Earth orbit to Moon orbit? And how much stages? For i.e. C12H22O11 + KNO3, polyethylene + oxygen or kerosene + oxygen.
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1answer
119 views

Why are inclined push-ups harder?

I came up with a random question which looked simple, but I can't work out the answer. The question is, why are inclined push-ups harder? And by inclined push-ups I mean push-ups with your legs on a ...
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2answers
80 views

The acceleration of the centre of mass [closed]

Given two balls that are thrown straight up in the air at a speed of $40 \:\mathrm{m/s}$, $0.10 \:\mathrm{s}$ apart. One ball is twice the mass of the other. The heavier ball is thrown second. ...
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1answer
53 views

Spring-mass system with complex spring constant

Suppose a system containing a mass $m$ on frictionless surface, attached by a spring to a wall. The spring's constant is complex, given by $K = K_1 + K_2i$, with $K_1 \gg K_2$. Write the ...
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1answer
30 views

Acceleration in an elliptical binary system

So I'm having a bit of a problem dealing with binary systems. I'm looking at acceleration in a stellar system and am not sure where to begin. Assuming both stars are of equal masses, they'd be ...
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1answer
99 views

Finding a Differential equation for falling chain

This is a chain wound loosely to a peg at the edge of a high platform. It has a total length of $L$ in feet and is hanging initially $x_{0}$ from the platform plus it's weight is $w\:\mathrm{lb/ft}$ ...
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0answers
21 views

Force and inclined plane

An incline of mass $m_2$ can move without friction on a horizontal plane. A block of mass $m_1$ is fixed to the incline with a piece of string. How does the system move when the string is burnt? The ...
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3answers
128 views

What happens if a machine controlled by me from Earth strikes the Earth? [closed]

SITUATION: Suppose I am a mad scientist and I have made a machine which has enough mass to push the earth. Now I am controlling the machine with a remote control with which I can change its speed, ...
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0answers
45 views

Calculate the amount by which the centre of a circular lake is depressed by the centrifugal force [closed]

This the problem that I intend to solve: The water in a circular lake of radius 1 km in latitude 60° is at rest relative to the Earth. Find the depth by which the centre is depressed relative to ...
-1
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2answers
58 views

Why is only one end at rest when a rope is attached to a cube? [duplicate]

I know there is something wrong in the way I think about physics generally, but I don't know what it is. Suppose there is a cube with a hook on one face and a rope attached to that hook (see ...
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2answers
68 views

Conservation of momentum when a shell is fired from a cannon

When a shell is fired from a cannon free to move on a horizontal surface and inclined at an angle say 45 degree with horizontal. Does relative velocity of shell with respect to cannon depends on ...
2
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1answer
55 views

If the Moon had a large piece blown out would it remain tidally locked?

I just saw this video on Sonic Adventure 2 trivia where it's mentioned that part of the Moon was blown up but in later games it's whole. It was explained away as the Moon simply rotating to show the ...
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1answer
55 views

When does an object rotates and translate at the same time?

I have a ruler on the table. If I push it with my finger on its end, it will rotate. but if I push it hard enough, it will rotate and slide slightly. Which force cause this sliding motion? and how ...
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7answers
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What does an undefined formula in physics mean?

I am trying to figure out how undefined formulas in mathematics relates to physics. Take the following formula for terminal velocity. $$V_\text{terminal} = \sqrt{ mg \over{c \rho A}} $$ Say we have ...
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1answer
33 views

Alternative method for pulley system not working

We have two a pulley system with two masses of 2kg and 3kg on two ends of a massless string. At the end of 5 seconds, the string breaks. How far up did the 2kg block move? Here's what I have tried:- ...
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1answer
25 views

Phase space orbit for a projectile [closed]

After playing around with drawing the phase space orbit for a harmonic oscillator I started wondering about the case for a free falling object. So the equations of motion are: $$ P = P_0 + mgt $$ ...
3
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1answer
121 views

Orbital equations of motion with respect to energy

Consider the equations of motion of an object in an orbit around a central body. We use an inertial frame originating at centre of mass of the central body: $$ \frac{d\mathbf{r}}{dt} = \mathbf{V} ...
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1answer
71 views

How to conserve angular momentum?

If i want to conserve angular momentum from the point of contact of the solid sphere and the ground how should I do it? I know we can use $mvh = I\omega + MvR$ ,if the collision is elastic. But in ...
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0answers
66 views

Uranus, the Physical model to change it's rotation axle

Uranus rotates pretty wierd, it's 90-degrees tilted; Why is Uranus's axis of rotation tilted? The best answer for this is; that at a distant point in its past, Uranus was struck by a very ...
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1answer
38 views

Example of physical phenomenon with zero velocity at some point that does not correspond to an extremum [closed]

For many students (at least mine), the vanishing of the derivative $f$ at some point means that the function is maximal at that point. The cubic function $f(x)=x^3$ shows this is false. Students ...
2
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2answers
56 views

What is the mechanism of heat exchange of a bouncing ball?

Imagine a falling ball on a perfectly hard ground. The kinetic energy will be first converted into a deformation of the ball, then the ball will restore it into kinetic and heat energy and recover ...
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1answer
136 views

Confusion about gravity

I understand the “rubber sheet” model of Relativistic gravity is just an illustration, and beyond the initial issues of mixing three dimensional objects with a two dimensional representation of 3D ...
2
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1answer
52 views

Calculating mass of an orbiting body with force and acceleration

I'm new to physics, and it's a lot to take in- but there is a problem that I really can't seem to wrap my head around- finding the mass of an orbiting body, like an asteroid. I've looked around a lot ...
1
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2answers
92 views

Why is kinetic friction less than static friction? [duplicate]

Ex: A wooden block is lying on a table. I am told that because the block is still, the microscopic surface irregularities form more complicated interlocking structures. Is it because the force of the ...
0
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2answers
69 views

How fast would someone travel by jumping out of a spaceship into space [closed]

If someone without any propulsion jumped from a stationary ship in space, how fast would they travel?
0
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3answers
186 views

Why does the work-energy theorem need to include internal forces?

Can anyone kindly explain me why work energy theorem must also include internal forces? The proof of work energy theorem is derived from Newton's laws of motion, but Newton's laws of motion don't ...
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1answer
52 views

Work done should be positive but it is coming out to be negative? [closed]

I have described a question in which this problem arises in the image below:
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1answer
90 views

Conservation of energy or conservation of momentum- which one is applicable in this problem?

There was this question from Kleppner and Kolenkow's Classical Mechanics: PROBLEM: And I found its solution from this Link: It is quite an extended solution and I am not drawing you into the ...
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3answers
153 views

Gravitational Force [closed]

If energy is represented by Acceleration=A, then am=F ams=W (ams)/t=P Acceleration is always present when motion is present, acceleration is the energy. Since gravity translates into ...