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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1answer
74 views
Given a potential energy function, find expression of the force of a particle?
This comes from an AP review packet. I'm given a potential energy functon, $$U(r)=br^{-3/2} + c,$$ where $b$ and $c$ are constants, and need to find the expression for the force on the particle.
...
3
votes
2answers
165 views
Firing machine question
Suppose we have a firing machine on a frictionless surface at point $x=0$. It fires a bullet of mass $m$ every $T$ seconds. Each bullet has the same constant velocity $v_0$. There's a body of mass ...
0
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1answer
38 views
Period of oscilation [duplicate]
Two masses $m_1$ and $m_2$ are connected by a spring of spring constant $k$ and slide freely without friction along horizontal track. What is period of oscillation? No force influence.
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1answer
54 views
Problem about moments and equilibrium. [closed]
A plank is on top of 2 branches. It is in contact at 2 points, A and B. The plank is 90 cm long. A is on the left of B. A is 15 cm from the left end of the plank. B is 20 cm from the right end of the ...
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0answers
42 views
Trajectory the body thrown at angle to the horizon
I need to simulate some body, thrown at some angle to the horizon and at some azimuth.
What would be $x(t)$, $y(t)$ and $z(t)$ involving $g(h)$, air resistance (with $\rho(h)$), Coriolis effect and ...
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votes
2answers
84 views
How to determine Center of Gravity? [closed]
I came across this question while having conversation with one person.
We know that Center of Gravity of a solid cube is at the intersection of connecting the opposite vertex of the cube.
Suppose, you ...
-2
votes
0answers
68 views
Man ,Pulley, block system? [closed]
In the figure $m_{A}=m_{B}=m_{C}=60 kg$. The coefficient of friction between $C$ and ground is $0.5$, $B$ and ground is $0.3$, $A$ and $B$ is $0.4$. $C$ is pulling the string with the maximum possible ...
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1answer
32 views
Why frequency and tension doesn't change in the two medium?
I am reading a book about wave mechanics. There are two different cord (one light and one heavy) connected together, one person waving the lighter one, the wave transverse to the right from the ...
2
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2answers
84 views
Parabolic motion (experiment)
We performed a laboratory, performing six releases of a sphere with angles $15^\circ,30^\circ,45^\circ,60^\circ,75^\circ,40^\circ$ a parabolic movement, took five distances for each angle, the initial ...
2
votes
1answer
109 views
Wedge and Sphere problem
A sphere of radius $R$ is in contact with a wedge. The point of contact is $\frac{R}{5}$ from the ground as shown in figure. Wedge is moving with velocity $20~\text{m/s}$ towards left then the ...
3
votes
2answers
58 views
Two-body problem questions
I am self studying the two body problem and I'm stuck on the following:
I have given $$\ddot{\vec{x}}_1= - G m_2 \frac{\vec{x}_1-\vec{x}_2}{|\vec{x}_1-\vec{x}_2|^3}$$ and $$\ddot{\vec{x}}_2= - G ...
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2answers
66 views
Eddy currents: Explanation of the force slowing down a moving metal plate
Suppose a solid metal plate moves trough a homogenous magnetic field $\vec{B}$ as shown in the following image. You will see that the plate will slow down (as long as not the entire plate is in the ...
1
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1answer
66 views
Movement of the particle in a magnetic field
This is the numerical question.
A particle having a mass of 0.05 mg carries a charge of $5\times10^{-6}C$. The particle is given an initial horizontal velocity of 5000 m/s, what is the magnitude ...
2
votes
1answer
120 views
Two masses attached to a spring
I'm trying to understand the solution of the following problem.
Two masses $m_{1}$ and $m_{2}$ slide freely in a horizontal frictionless track and are connected by a spring whose force constant is ...
0
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1answer
83 views
Energy needed to lift and bring down an object
A mass of 0.5 Kg needs to be moved from point A to another point (B) which is 1 meters above point A. The time for this movement should be 0.2 seconds, then the mass is kept at position B for another ...
2
votes
3answers
147 views
Newton's Second Law Equivalent in rotational dynamics
The law that
$$\frac{d\vec{L}}{dt}= \vec{T}$$
where $\vec{T}$ is torque about a frame's origin $o$ and $\vec{L}$ is the angular momentum about that origin $o$.
Can this law be ultimately (always?) ...
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3answers
130 views
Why does a rod rotate?
I'm a physics tutor tutoring High School students. A question confused me a lot.
Question is:
Suppose a mass less rod length $l$ has a particle of mass $m$ attached at its end and the rod is ...
2
votes
1answer
68 views
Convert a 200mm linear stroke into 90 degrees motion
Can anyone help me Convert a 200 mm linear stroke into 90 degrees motion with as much mechanical advantage as possible or into two 90 degrees motions with as much mechanical advantage as possible?
...
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0answers
15 views
Collision response between a mass and a line attached to two masses [closed]
I'm currently in the making of a small simulation program and, as I am very new to physics, I am struggling with what seems to be a simple 2D collision response problem.
I spent quite some time ...
0
votes
0answers
37 views
Compound pendulum clarification?
I read in a book the following about compound pendulum and small displacements:
There are two points only for which the time period is minimum.
there are maximum 4 points for which the time ...
7
votes
1answer
255 views
Is acceleration an average?
Background
I'm new to physics and math. I stopped studying both of them in high-school, and I wish I hadn't. I'm pursuing study in both topics for personal interest. Today, I'm learning about ...
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0answers
54 views
Scaling arguments for the Contact mechanics between two elastic spheres
I am studying a bit granular dynamics and I have seen that two spheres of radius $R$ in contact with a contact area of radius $a$ would need an applied force $F$ on this two spheres that is nonlinear ...
0
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0answers
35 views
Mechanics: collision & rotation [closed]
A rod AB of mass M and length L is lying on a horizontal friction less surface. A particle of mass m traveling along the surface hits end A of the rod with a velocity 'v' in a direction perpendicular ...
0
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0answers
36 views
How can I find the frequency? [duplicate]
Grocery stores often have spring scales in their produce department to weigh fruits and vegetables.
The pan of one particular scale has a mass of 0.5 kg, and when you place a 0.5 kg sack of potatoes ...
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0answers
51 views
Frequency with the spring scale [closed]
Grocery stores often have spring scales in their produce department to weigh fruits and vegetables.
The pan of one particular scale has a mass of $0.5 kg$, and when you place a $0.5 kg$ sack of ...
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votes
2answers
161 views
Nonuniform acceleration due to rubber rope
What I want:
I have a rubber rope which is $5m$ in length when not stressed and is able to stretch about $100\%$ (to $10m$ long). I want to accelerate a constant mass horizontally, which has ...
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2answers
69 views
Potential energy during vertical fall
Suppose I have a weightless spring connected perpendicularly to the ground, and it has on top of it some weightless surface. Now, I release some sticky object from height $h$ above the system of light ...
4
votes
1answer
83 views
How did Newton find out force has something to do with acceleration?
Its about Newton's second law of motion,
$$F=ma.$$
It says the acceleration of an object is directly proportional to the net force and is inversely proportional to the object's mass. Yes I can ...
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3answers
72 views
Mass equals Moment of inertia when constant density?
I have found equation for moment of inertia $(J)$. I'm calculating $J$ for hemisphere, with rotational axis $Z$.
$$ J = \iiint\limits_V r^2 \cdot \rho \cdot dV $$
But if $\rho$ is constant ...
1
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2answers
144 views
Semi-major axis and ellipticity of a binary system?
In the image below (source at bottom), it seems to be suggesting that
\begin{equation}
a = a_{1} + a_{2}, \hspace{8cm}(1)
\end{equation}
where $a_{1}$ and $a_{2}$ are the semi-major axis of the ...
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0answers
33 views
Baseball rolls off desk [closed]
An autographed baseball rolls off of a 1.0 m
high desk and strikes the floor 0.67 m away
from the desk.
How fast was it rolling on the desk before
it fell off? The acceleration of gravity is
9.81 m/s2.
...
0
votes
1answer
76 views
Simple harmonic oscillator system and changes in its total energy
Suppose I have a body of mass $M$ connected to a spring (which is connected to a vertical wall) with a stiffness coefficient of $k$ on some frictionless surface. The body oscillates from point $C$ to ...
0
votes
2answers
70 views
What's the motion of this yoyo under external force will be?
A yoyo on a horizontal table is being pulled by a string to the right, the table is not frictionless. If we only know that the object doesn't slip, how do we know if the string is winding up or ...
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0answers
44 views
Dynamics of an object hitting a spring [closed]
In a one dimensional universe, there is an object of mass m, heading towards a spring (which is attached to a wall of infinite mass) of spring constant k, at a constant speed of u (i.e. acceleration ...
3
votes
1answer
75 views
How do I calculate how something should stay in position under gravity?
Excuse me if this too simple a question - I'm not a regular (consciously) user of physics.
I have a ship in space and it is under the effect of three moons. The ship can rotate and thrust to move ...
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1answer
48 views
Forces on a particle moving in a vertical circle
In the diagrma, a particle (A, mass 0.6kg) is moving in a vertical circle. The question is: When it gets to the lowest point, what is the tension in the light rod that is between the center of the ...
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3answers
93 views
Parachute in vacuum
Consider that the earth is vacuum. Consider a person of weight 100 kg is falling from sky with an parachute . He is free falling at height of 3000 m. When will he reach the ground? What would happen ...
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1answer
102 views
Earth's rotation isn't that orbit?
If the earth is rotating at some $465~\text{m}/\text{s}$ at the equator and that's really fast.
Shouldn't we in that case be in orbit with the earth just not fast enough?
How fast do we need to ...
2
votes
0answers
92 views
Why did increasing the Ackermann geometry in my race car make it faster in corners?
Ackermann geometry is used to account for the different radius arcs that the front tires follow when the steering wheel is turned from center. It's often expressed as a percentage: e.g. 25% Ackermann, ...
1
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0answers
51 views
Calculating pressure in accelerated fluids in closed and open vessels?
The question asked was "what should be the acceleration such that the pressure at both the points marked by thick dots be equal? the vessel is open and cubic with side 5m?"
Initially i considered ...
4
votes
2answers
117 views
If the moon was rapid enough would it be able to orbit the earth from a close distance?
If the moon was close in orbit that it's surface was like 100 km away from the earth's surface. And it had a large enough angular velocity will it be able to hold orbit?
If this was possible, is ...
2
votes
3answers
137 views
Is Newtonian gravity consistent with an infinite universe? [duplicate]
Let us assume that we have have an infinite Newtonian space-time and the universe is uniformly filled with matter of constant density (no fluctuations whatsoever), all of it at rest. By symmetry, the ...
7
votes
4answers
490 views
What causes a soccer ball to follow a curved path?
Soccer players kick the ball in a linear kick, though you find it to turn sideways, not even in one direction. Just mid air it changes that curve's direction. Any physical explanation?
Maybe this ...
0
votes
1answer
33 views
Find the bending moment of a pole attached to a moving block
I'm having trouble with the following problem.
What I've done so far:
x-y is the usual coordinate system.
$a=\frac{F}{m}=\frac{800}{60}$ and the y component of this is $a_y=a\sin{60^\circ}$.
To ...
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votes
3answers
100 views
Solve for Initial Velocity of a projectile given Angle, Gravity, and Initial and Final positions?
I've found equations http://www.physicsclassroom.com/Class/1DKin/U1L6a.cfm for solving everything (and rearranged to solve everything) to do with projectile motion EXCEPT this, even though it should ...
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3answers
112 views
Projectiles and escape velocity
Q: The escape velocity for a body projected vertically upwards from the surface of earth is 11 km/s. If the body is projected at an angle of $45^\circ$ with vertical, the escape velocity will be?
...
2
votes
2answers
115 views
Whats the anti-torque mechanism in horizontal take-off aircraft?
In most helicopters there is the anti-torque tail rotor to prevent the body from spinning in the opposite direction to the main rotor.
What's the equivalent mechanism in horizontal takeoff single ...
0
votes
1answer
84 views
Kinematics with non constant acceleration
A particle experiences an acceleration described by
$$
a=kx^{-2}
$$
where x is the displacement from the origin and k is an arbitrary constant.
To what value does the velocity v of the particle ...
0
votes
1answer
56 views
Hollow stone columns provide more support?
In history class in elementary school I remember learning that the Greeks would build their stone columns hollow because they thought this provided more support. Is it true that a hollow column is ...
15
votes
5answers
274 views
Does the mass point move?
There is a question regarding basic physical understanding. Assume you have a mass point (or just a ball if you like) that is constrained on a line. You know that at $t=0$ its position is $0$, i.e., ...
