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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2answers
183 views

Will an object falling into Earth's orbit start spinning?

Assume an object falls towards Earth (I've drawn a hyperbolic orbit, but this would apply to any orbit). The object starts at $A$, and at this point it is not rotating i.e. an observer on the object ...
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1answer
36 views

Newton's third law of motion versus Work

Newton third law of motion says that "To every action, there is always an equal and opposite reaction". The vector study tells us that if two vectors are of same nature and equal magnitude but ...
0
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1answer
38 views

Hooke's Law vs. Elastic Potential Energy

I am currently learning about elastic potential energy and this is a question that was given to us by my teacher: When a 13.2-kg mass is placed on top of a vertical spring, the spring compresses ...
0
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3answers
55 views

Object falls and hits ground - which forces are involved to change its momentum?

When an object falls and hits the ground - which forces are involved to change its momentum? Should $m\vec{g}$ be taken into account of the forces that were involved in the change of momentum?
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2answers
108 views

Is the center of mass of an object just a convention?

I am currently studying moments. The concepts are fairly obvious, but there is one thing I don't understand: the concept of center of mass. Why do we consider that the weight of a uniform object is ...
0
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1answer
17 views

Force of tension on both sides of one string- 2 questions

Here's something I want to ask you guys about: Many times downward N1 and N2 are ignored in exercises. Why? If forces of tension are balanced by each other, why won't objects just fall? Cheers ...
0
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1answer
15 views

Moving a block up a ramp

Would this be a valid way to approach this? Find the force needed to push a block of mass 5kg to the top of a ramp whose length is 1m and makes a $30^\circ$ angle with the ground. $$W_{grav} = ...
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1answer
21 views

Do all thing move against gravity with -9.8 meter per second squared acceleration?

If I throw a ball to height h above the earth's surface and then shoot a bullet that reaches the same height but would there be same quantity of acceleration produced in both?
0
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4answers
53 views

Using formula for work with distance of 0m [duplicate]

Consider this: Wind is pushing a huge rock towards me at with massive force at 2m/s. I push against the rock at equal force so the rock stays still. I am clearly "working" very hard, using a lot of ...
1
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2answers
29 views

Calculate damping constant / coefficient

I am trying to graphically simulate a series of springs in 2D. Now one of the forces I am stuck with calculating is the damping force. The given formula is $F = -k_d v$. I know that $v$ is the ...
2
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2answers
62 views

What is the meaning of the negative sign in $W = -\Delta U$?

What is the meaning of the negative sign in $W = -\Delta U$ ? As far as I understand, $W = -\Delta U = -(U_f - U_i) = U_i - U_f$. While $U_i$ is the initial potential energy (before applying the ...
2
votes
1answer
38 views

A conical pendulum. A textbook claims one can start the circular motion in an unintuitive way

A textbook claims that if you hang a mass from a string that's attached to a rod (so that the string is parallel with the vertical axis) and you spin the rod fast enough, you can put the mass into ...
0
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1answer
60 views

Why oobleck does not obey Newtonian dynamics? [duplicate]

In the following post we can see that some guys are walking on Non-Newtonian fluids. As far as I know that, we can not predict the exact amount of strain if we predict some forces. therefore the curve ...
0
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0answers
36 views

Gravitational acceleration by the moon at a given point in Earth

Given the following scenario: Where: The big circle is the Earth The small circle is the Moon $d$ is the distance between their center of mass $R$ is the radius of the Earth Assume that a person ...
0
votes
1answer
24 views

Who is moving and with who's relation?

What if we are in a cube of 3×3 m  which is further enclosed in a sphere of radius 50 m? And the sphere start to rotate on its own axis would we experience force? If not then what happens if there is ...
1
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0answers
23 views

A fort is on the edge of a cliff of height $h$. Find the greatest horizontal distance at which a gun in the fort can hit a ship [closed]

A fort is on the edge of a cliff of height $h$. Find the greatest horizontal distance at which a gun in the fort can hit a ship, if $\sqrt {2gk}$ be the muzzle velocityof the shot. Find also the ...
0
votes
0answers
33 views

Angular velocity of sphere rolling on a sphere [closed]

A homogeneous solid ball of radius $r$ rolls without slipping on the surface of another larger homogeneous semi-ball of radius $R$. The small ball begins at rest on the very top of the larger ...
1
vote
1answer
78 views
+200

Imposing symmetries on asymmetrical dynamic systems

Let us say we have a one dimensional system of masses connected by springs. All the masses are equal and the springs alternate with spring constants of $k$ and $6k$. The appropriate way to analyze ...
0
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0answers
45 views

What is the relationship between the Young's modulus of a material and the elasticity of a free fall collision

I'm coding a 2D physics simulator based around the Newtonian physics principles with some alterations due to computation limits and I am at the stage of creating a collision event between a planetary ...
1
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0answers
38 views

Accelerating rockets by periodic explosions? [closed]

Since in the outer space friction is almost 0, couldn't we accelerate a rocket to reach much faster speeds than that of the current limit by periodically starting and stopping the engines? I think ...
0
votes
1answer
22 views

What happens when a high speed motor tries to drive a heavy car? High torque?

I'm trying to figure out what would happen if a really high speed motor - which has enough power to drive a car, but very high RPM & very low torque - tries to move a car. Does it get stuck ...
0
votes
1answer
20 views

why is there an 'equal' and opposite reaction if the force depends on the momentum?

If you have a large mass and a small mass that collide, the large mass reacts according the smaller mass's momentum and vise versa. For it to be consider 'equal' doesn't that mean they have to feel ...
4
votes
1answer
107 views

What made Kepler think that orbits are not circular which came to be elliptical?

Kepler formulated his laws in a sort of time where human began to believe in heliocentric universe and telescope was not yet invented/ discovered. So what made Kepler think that orbits aren't ...
1
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0answers
35 views

How velocity progresses over time with a non-constant acceleration? [closed]

A $0.25\text{ kg}$ sphere of radius equal to $0.07\text{ meters}$ is dropped from rest from the top of a building. Granted that it will not hit the ground before, when and after what distance ...
0
votes
1answer
37 views

Kepler's laws: show the planet always stays in the same plane?

I know angular momentum $L=q \times p$ is conserved, where $p=L_{\dot q}$ is linear momentum. How to apply this to a planet orbiting the star, described by the position vector $q$ relative to the ...
0
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2answers
49 views

What is causing the normal force in circular motion?

In the picture, at point 2 (the bottom of the ramp) the normal force of the object has a greater magnitude than weight. I understand that the normal force has to be greater than the weight since the ...
0
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0answers
20 views

Verification of mass density function in continuum mechanics

I'm having problems knowing where to go with this question: Suppose that a certain material initially fills an open region $\mathcal O\in\mathbb R^3$, with $\Omega:=[-1,1]^3\in\mathcal O$ , so ...
1
vote
1answer
47 views

Determine the value of $g$ with rolling ball

At first, I thought the value of $g$ ($9.8m/s^2$) could be determined simply by placing a ball at the top of a ramp at a known height. The ball was released with no initial velocity, and the final ...
2
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2answers
48 views

Air Drag in orbit

Artificial satellites don't orbit the earth forever. Eventually the Earth's atmosphere, thin as it may be up there, will bring them down. But did you know the linear speed of a satellite in a near ...
0
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0answers
22 views

Newtons 2nd law and longitudibal dynamics of bicycle

When a bicycle (of gross vehicle mass $m$) accelerates ($a$) forward, such that both the wheels are in pure rolling (no slipping), then: static friction ($f_{s1}$) acts on the front wheel backwards, ...
0
votes
1answer
15 views

Writing collision equations with the help of coefficient of resistitution

Suppose we have a frictionless surface and a small particle of mass $m$ which collides with velocity of $V$ with stationary particle of $2m$ elastically. I know how to deal with this simple problem ...
-2
votes
3answers
57 views

Air resistance force [closed]

How do I find the air resistance force and the maximum air resistance force when all I'm given is the mass, terminal velocity, and I know it's falling in quite air? I found a formula online but it ...
5
votes
5answers
2k views

How could a cord withstand a force greater than its breaking strength?

How could a 100 N object be lowered from a roof using a cord with a breaking strength of 80 N without breaking the cord?? My attempt to answer this question is that we could use a counter weight. But ...
3
votes
10answers
1k views

Why does it take a projectile as long to get to its apex as it does to hit the ground?

I was once asked the following question by a student I was tutoring; and I was stumped by it: When one throws a stone why does it take the same amount of time for a stone to rise to its peak and then ...
0
votes
1answer
17 views

Normal force for car banking turn vs object sliding down slope

When describing an object sliding down a slope, we say that the normal force is less than the weight of the object, and that the vector weight minus the normal force equals the force with which the ...
0
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0answers
17 views

weightlessness and forces conceptional question

I am currently learning about forces and newton's laws of motion. I have a question in my book which I don't understand though... Here it is: (note: I dont want the answer I just want to understand ...
1
vote
1answer
35 views

When do we assume that a rope has different tensions in different places?

Working a problem with 2 pulleys and masses in class this week the professor at one point assumed that the tension on the two sides of a pulley would be different. Every other time we've done a ...
0
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0answers
29 views

Can energy be extracted indefinitely from a mass dipole/mass negative mass pair in perpetual motion?

Some days ago I have read this short piece of article by Hammond which caused me to revisit the theoretical properties of negative mass. It is known that a pair consists of ordinary mass and negative ...
1
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4answers
118 views

Conservation of energy, and Newtonian physics that does not fit

Here is a theoretical example where the energy into the system does not mach the energy output. There is no friction or air resistance. A sledge with a rocket engine attached to it is lying still on ...
0
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2answers
67 views

A simple pendulum

The idealized simple pendulum model (see the following figure) assumes that at every point of time the string to which the bob is attached exerts an equal and opposite force on the bob as does the ...
-1
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1answer
78 views

A twist on the leaning ladder problem

For the first part, I know will need to form moment equations and resolve horizontally and vertically. But how do I decide which position to take for the dog while I form moment equations?
0
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2answers
35 views

Given the radius and angle of a frictionless banked curve, is it possible to find centripetal force?

A car is driving on a frictionless banked curve of radius 45 metres and 25 degrees. Is it possible to find centripetal force? If not possible, explain why.
0
votes
1answer
73 views

Conservation of momentum and impulse [closed]

This exercise comes from Halliday's Physics. Z A 2,9 ton weight falling through a distance of 6.5 ft drives a 0.5-ton pile 1.5 in. into the ground. Assuming that the weight-pile collision is ...
0
votes
1answer
69 views

Motion in the gravitational field along a trajectory [closed]

A point particle of mass $m$ is moving in the gravitational field along some trajectory which is described by the function $y=y(x)$, which is in a vertical plane and is continuous. Initial ...
0
votes
0answers
30 views

Ideal Bullet Block

What if in the experiment by Veritasium Bullet Block Explained, we used an ideal block and bullet, so that the collision is perfect elastic, and the bullet doesn't stick to the block after hitting it? ...
0
votes
1answer
40 views

On a banked turn, why isn't weight in x the centripetal force?

Why does the x component of the Normal force act as centripetal force in a banked turn and not the weight component in x? I know it may sound silly but please respond.
0
votes
1answer
47 views

Two body problem with given start positions and velocities [duplicate]

I am trying to program a $n$-body problem simulation. To calculate the position and velocity after a time-step I want to split it in multiple 2 body problems. Now I am stuck, trying to find the ...
0
votes
2answers
48 views

Direction of friction vector when acceleration is zero

There is a box on a ramp, there is Wx that makes it fall, Tension that pulls it up the ramp (a rope) and Friction. The thing is, how can I determine the direction of the friction? For me, friction ...
2
votes
3answers
49 views

An object is placed on an inclined plane. Does it roll? [closed]

An object is placed on in inclined plane. There may or may not be friction, your choice. My question is, how do we figure out whether or not it rolls? For example a sphere rolls but a cube doesn't.
1
vote
1answer
43 views

Pendulum forces in orbit

On Earth a pendulum is governed by a set of equations, relating the angle of the swing, the mass etc. However with a pendulum in orbit there is no fixed point (assume 2 masses attached via a string). ...