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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11 views

Electromagnet force equation clarification

So, from a previous previous question, I know what plane the force from an electromagnet will affect a ferromagnetic material in. I thought that would be enough, but working through some problems ...
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2answers
15 views

Diagram of forces exerted on objects

Assuming that there is an interaction between 1 and 3 (they attract each other), what are the forces between 1 and 2? I know it is as if the force acts on a different body (1+2), but I want to know ...
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0answers
18 views

Where is the maximum center of mass so it doesn't fall over? [on hold]

I have some sort of barrow with brakes, which its deceleration due to the braking never makes the crate slide down: it results in $\mathbf{a} \leq g(\mu\cos\theta - \sin\theta)$ (note that it can ...
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2answers
78 views

Pulling apart two interleaved phone books

The TV show Mythbusters had an episode in which they interleaved two phone books and dramatized how hard it was to pull them apart. (A long time ago, a phone book was a book that had an index of phone ...
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0answers
22 views

Effect of an asymmetric weight distribution on a hack squat machine

In a hack squat machine (see figure above), does it matter if I put more washers on one side? May this asymmetry cause an asymmetry of my effort in performing this exercise? For example, if I put ...
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5answers
59 views

Forces while squeezing a toothpaste tube

When I squeeze a tube of toothpaste, I am working with 2 squeeze forces toward tube. What causes the toothpaste to go out of the tube? (instead of remaining stationary)
1
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1answer
19 views

Calculate coefficient of friction from deceleration with and without conservation of energy

How can I solve the following problem? A block that moves at the speed of 120 cm / s keep going for 70 cm before stopping. What's the coefficient of friction between block and table calculated ...
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1answer
74 views

Can a ball stay still while laying on a inclined plane?

Suppose there is a ball on an inclined plane. So, there are three forces acting on it: normal force from the plane, gravity (which can be decomposed in the component of gravity perpendicular to the ...
3
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2answers
69 views

Why are some forces not included in the sum of forces?

I was given the following notes in class: 4.32 A skier of mass $65.0\text{ kg}$ is pulled up a snow-covered slope at constant speed by a tow rope that is parallel to the ground. The ground ...
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0answers
16 views

Linear slider motor mount location [on hold]

I'm currently designing a linear camera slider, that will be used to hold camera equipment weighing just about 15 Kgs including all of the lenses and monitors and everything else. For those who ...
-2
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0answers
14 views

Calculate the maximum displacement of mass 'm' body, when the system is released from rest at euqilibrium? [on hold]

Image Describes about a system at equilibrium, which consists of springs, pulley, and a body of mass 'm'.
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2answers
87 views

Why isn't work relative?

Acceleration and displacement can be defined relative inertial frames. For example, a body moving with constant velocity on top of another moving with the same velocity will have zero displacement ...
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2answers
112 views

If an asteroid were threatening the Earth, could I deviate it just by jumping on it?

An impact by a 10 kilometres asteroid on the Earth has historically caused an extinction-level event due to catastrophic damage to the biosphere. There is also the threat from comets coming ...
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3answers
97 views

How to calculate when wheels are better than legs?

We all know that it uses less energy to go by wheeled transport than walking if the terrain is smooth and there are not too many hills. We also all know that when going up steep hills we get off ...
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0answers
20 views

Restricted three body problem

I have the restricted three body problem, which corresponds, to the equation $ \ddot a-2\dot b -a= \displaystyle\frac{\partial U}{\partial a} $ $ \ddot b +2 \dot a-b = \displaystyle\frac{\partial ...
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1answer
25 views

Horizontal distance covered by an object from an initial height to the ground

We are given: An angle $\theta$ with respect to the ground, its initial height $h_0$ and the final distance $d$. How can we find the initial velocity from this information? I tried a bunch of things, ...
0
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1answer
31 views

Reflection - reaction force direction

Let's say object hits a wall. When the object is reflected does the direction of the reaction force caused on the wall looks like the red arrow ? Does that direction depends on how "strong" object is ...
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0answers
17 views

Action and Reaction on two bodies [duplicate]

If the action and reaction are both equal and opposite then why a body would move? The force exerted by me on the body must be counterbalanced by the force exerted by the body on me.
2
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1answer
58 views

How to calculate wasted energy

Suppose you are pulling a weight along a track at an angle (in the picture 45°). If the object is dislocated by a distance $D_{45}$ let's assume that the mechanical work done on/energy transmitted to ...
3
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1answer
85 views

Could $\int (\ddot\phi + \mu\dot\phi^2)d\phi$ ever be negative? How to show it?

I am working on the following problem: Given a mass $m$ at rest at the base of an incline surface shaped like 1/12th of a circle with radius $R$. The mass is pulled up the incline by a rope that ...
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0answers
38 views

Projectile under quadratic air resistance force

So here's the problem background: A projectile of mass m is shot straight up with initial velocity $v_0$ and feels a quadratic air resistance force of the form $F = −kv^2$, where $k ≡ mg/u^2$. ($k$ ...
3
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0answers
41 views

Acceleration: A ball sliding down the inside of a semicircular bowl

Edit: To clarify, this is a homework question. But I couldn't care less about getting the answer to this specific question as it's not even assigned yet. It looks interesting and I want to understand ...
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0answers
25 views

Confusion regarding a method of writing constraint equations

I came across a method for writing the constraint equations known as "The Virtual Work Method".I am quoting the exact language of the text(well,not exactly the exact)- Consider the atwood machine ...
4
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2answers
106 views

Giant leap of the space goat

This problem was inspired by this Math.SE post and similar problems involving tethered animals. A space goat is tethered to the north pole of a spherical asteroid of uniform density and radius $a$ ...
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1answer
27 views

How similar is comparison between the principle behind Newton's Cradle versus AC Current moving down a transmission line?

Anyone who has taken high school physics has seen the following assembly. You drop one ball from the left hand side and the ball from the farthest right hand side gets knocked away. This is to ...
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0answers
33 views

Position Vector confusion [on hold]

I am having a little trouble understanding why the position vector r in calculating the $v_a$ is given by $225/\sqrt2$ (-i -j) If it is the position of C with respect to A shouldn't it just be $225$ ...
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2answers
59 views

Time derivative of angular velocity in rotating reference frame

I am going through a section in a textbook regarding the Newton Euler equations for a system of rigid bodies (robotics text). There is a particular line in the derivation I don't understand, I've ...
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1answer
26 views

Determining the force of an explosion, is it external or internal?

A time bomb put inside a box is left into the vacuum: it explodes...the box coverings starts moving I want to ask: is the force behind sudden acceleration internal or external I am confused about ...
0
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1answer
33 views

How to calculate the buoyant force on a balloon at different altitudes [duplicate]

For a project into balloon simulation I'd like to know how the force on a balloon changes with altitude: I know that the Buoyant force on a balloon is: $F = (\rho_{air} - \rho_{helium})gV$ Using ...
0
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1answer
38 views

DO the condensed photon particles-waves-longitudinal-waves exist? [on hold]

This is kind of hard to explain, because weird as it sounds, i have experienced a phenomenon that i would like to see if it exists and if i can explain it mathematically. The longitudinal waves of ...
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0answers
18 views

Change in momentum [duplicate]

A cube has a side length of 20 cm. An atom in the gas moves around the cube as shown. It continually bounces off the four lateral walls of the cube. The atom has a mass of 6.6×10−27 kg. Because of the ...
1
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0answers
23 views

Elastic Collision [on hold]

A cube has a side length of 20 cm. An atom in the gas moves around the cube as shown. It continually bounces off the four lateral walls of the cube. The atom has a mass of 6.6×10−27 kg. Because of the ...
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0answers
18 views

Find $r$ and $\theta$ given orbital elements [on hold]

Calculate $r$ vector and $v$ vector in AU and AU/TU respectively for the Halley's comet on September 12, 2014 given: 𝑎 = 17.9 AU 𝑒 = 0.967 𝑖 = 2.8274 rad Ω = 1.0210 rad 𝜔 = 1.9513 rad 𝑀 = 0 rad ...
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0answers
18 views

Determine radius, speed, radial and tangential component of velocity [on hold]

I need help mainly with the first question. If you can solve also the second problem,I'd greatly appreciate it.
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1answer
49 views

Earth-Moon system

While learning about motion of centre of mass, I came across this statement online, It is also more accurate to say that the Earth and Moon together revolve about their common center of mass. ...
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0answers
27 views

What are the most commonly misunderstood/explained everyday phenonmon, and how do they really work [on hold]

So, there are all kinds of 'standard' explanations that people just 'know' about how things work which are wrong. The sort of explanations a dad may give to their son when he asks the infamous "why" ...
4
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4answers
466 views

Quantum mechanics threshold

First of all I beg your forgiveness as I am not a physicist and the question I am going to ask may sound silly. I am aware that beyond a certain threshold in the hierarchy of building blocks of ...
0
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1answer
56 views

energy required to start and then stop rotating an object, when we have gravity

Imagine an arbitrary object with center of mass at the red dot in the picture, rotational inertia from the point of the hanging: I, hanging from a fixed point, what is the energy required to start ...
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0answers
12 views

Question regarding a two block system and a viscous force

I'm just looking to set up a free body diagram for this scenario and I'm having a bit of trouble understanding what's going on. The problem states, "A rectangular block of mass $m_1$ lies on top of a ...
-2
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0answers
27 views

Particle Acceleration in three dimensions [on hold]

So here is the problem I dont know how to approach it.
5
votes
3answers
403 views

Energy not conserved with accleration by a constant force

Suppose I have an object with mass $m$ in vacuum that I propel by applying a constant force, $F$, on it, with a rocket engine that I supply a constant amount of energy, $\frac{\delta ...
-2
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0answers
16 views

Find acceleration along normal and tangent [on hold]

A small block can move in a straight horizontal line a along AB. Flash lights from one side projects its shadow on a vertical wall which has horizontal cross section as a circle. Find tangential & ...
1
vote
1answer
339 views

How fast must a torus spin to have a felt gravity? [on hold]

Given a rotating torus (like a gyroscope or a rotary) with a radius of 1km, how fast must it rotate to have someone inside the torus feel normal gravity of 1G?
1
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3answers
82 views

Escape velocity of satellites

I know that the equation for it is $$v^2 = \frac{2GM}{r},$$ and with that, the rocket should be launched at that speed. But could it go much slower spending much more fuel to escape from gravity ...
1
vote
1answer
64 views

Question about torque and center of mass [duplicate]

If a yo-yo's string is not attached to anything and the yo-yo is dropped, it is obvious it will fall at $g$. In this scenario, Tension of string = 0. If a yo-yo's string is attached to a cieling and ...
17
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5answers
4k views

Is this scene from the A Team explainable by Physics?

This scene (youtube link) from the movie The A-team, the four members are in the tank and its falling from the air, they fire the canon and it slows the tank from falling for a moment before falling ...
1
vote
3answers
48 views

Why does the work done by an internal force differ from the work done by external force?

Let's consider the following situation. We put a body of mass $m$ at a distance $A$ from the center of Earth. We let the Earth attract the body and analyze the situation at a point $B$, closer to the ...
9
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1answer
91 views

How can a planet gravitationally capture objects?

I would expect that any asteroid or other object originating far away but passing near a planet would pick up speed and energy as it approaches, but unless it comes into contact with the atmosphere ...
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1answer
34 views

Projectile with air resistance [duplicate]

If you have a projectile with these variables. $x_0 = 1v_{0x} = 70, y_0 = 0, v_{0y} = 80, a_x = 0, a_y = -9.8$ I know how to plot these points with this equation. $$ x = x0 + (v_{0x})t + 1/2((a_x)t^2) ...
0
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2answers
43 views

Deriving Time from Acceleration, Displacement, and Initial Velocity

I know the equation for displacement as a function of time is $$\vec{s} = \vec{v_i} \Delta{t}+\frac{1}{2}\vec{a}\,(\Delta t)^2$$ I need to solve for $\Delta t$ I'm having problems rearranging to do ...