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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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
102 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
106 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 ...
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102 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, ...
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62 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 ...
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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 ...
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3answers
145 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 ...
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4answers
564 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 ...
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1answer
37 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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3answers
117 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
126 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?
...
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2answers
132 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 ...
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1answer
94 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 ...
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1answer
58 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
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5answers
282 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., ...
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1answer
138 views
How do you find (initial) velocity using conservation of energy?
Without mass; only time, distance, and height is given. For example:
For this lab, the reference level was 100cm above ground therefore the height of the object was 10cm. I determined time and ...
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1answer
39 views
Finding the acceleration at an angle
"What's the maximum acceleration you can achieve in a a water-slide at a 34 degree angle (If you can't use your arms and legs)"?
This is the free-body-diagram that I drew, assuming $g = 10m/s^2$:
...
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1answer
59 views
Direction of the torque
In each one of the following figures there's a pole of length $1.2
\text{m}$ and there's a force $\vec F = 150 \text{N}$ acting on it.
Determine the torque that is created by the force relative ...
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1answer
90 views
Gravitational field v.s. Physical variable?
I went to a talk on Newtonian mechanics some time earlier and the speaker said, and I quote,
Newton's equations of motion admit a larger symmetry group than the Galilean group alone. Therefore, ...
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3answers
147 views
Non-SHM oscillatory motion
How to solve these kind of questions , where $|F| \propto x^2$?
How to find time period and velocity type related things to the oscillatory motion?
...
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3answers
138 views
What needs to be integrated to solve this problem?
An object is placed on a frictionless table with its one end attached to a cord which is connected to a pulley and the tension is maintained constant at 25 N. what is the change in kinetic energy ...
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1answer
165 views
Cylinder rolling down an inclined plane held by a string
A cylinder of mass M and radius R is in static equilibrium as shown in the diagram. The cylinder
rests on an inclined plane making an angle with the horizontal and is held by a horizontal string
...
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1answer
68 views
What Speed Would an object need to leave the earth at to reach L1? [closed]
Let's say the Earth is an airless sphere. What speed would an object weighing 1 kg need to leave the surface at in order to get to and be motionless at L1, where the Moon's gravity becomes stronger ...
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5answers
193 views
Why is momentum conserved (or rather what makes an object carry on moving infinitely)?
I know this is an incredibly simple question, but I am trying to find a very simple explanation to this other than the simple logic that energy is conserved when two items impact and bounce off each ...
2
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2answers
130 views
Elastic collision and spring
Bodies $A$ and $B$ are moving in the same direction in a straight line with a constant velocities on a frictionless surface. The mass and the velocity of $A$ are $2 \text{kg}$ and $10 \text{m/s}$. ...
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2answers
334 views
Explanation that air drag is proportional to speed or square speed?
A falling object with no initial velocity with mass $m$ is influenced by a gravitational force $g$ and the drag (air resistance) which is proportional to the object's speed. By Newton´s laws this can ...
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1answer
74 views
Newton's second law?
$F=ma$. A car strikes a wall at 60 mph. Its acceleration is zero at the time. The force of the car against the wall or vice versa is? To look at the car the force is not zero. Please explain.
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0answers
119 views
Elastic collision of rotating bodies
How would you explain in detail elastic collision of two rotating bodies to someone with basic understanding of classical mechanics?
I'm writing simple physics engine, but now only simulating ...
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0answers
61 views
How much energy would it take to move the asteroid that has been implicated in the dinosaur extinction by a few centimeters? [closed]
One of the greatest mass extinctions occurred about 65 million years ago, when, along with many other life-forms, the dinosaurs went extinct. Most geologists and paleontologists agree that this event ...
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1answer
101 views
Pendulum question
A small ball of mass $m$ is connected to one side of a string with
length $L$ (see illustration). The other side of the string is fixed
in the point $O$. The ball is being released from its ...
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3answers
176 views
Is the tension in both ends the same (on a massed string)?
If two blocks lay on a table and I pull the second block, as shown in the picture below. Is the tension in both ends of the string the same? (The string has a mass)
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2answers
103 views
Accelerating an elevator
A person is standing on a weighing scale in an elevator in upward acceleration.
Let $N$ be normal reaction force exerted by the weighing scale to the person (upward).
It is known that the person ...
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1answer
171 views
Why is momentum conserved when a ball hits a vertical wall?
Almost in every book on physics, there's an example of conservation of momentum when the ball that is moving horizontally in the air, hits some massive wall. They claim that the return speed of the ...
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1answer
110 views
rate of change of spring potential energy $\frac{dU}{dt}$
Suppose we have a setup like this. In orange are two wooden sticks sort of things, and they are attached to the block of mass $m$(as usual) at a joint which is hinge type something. A similar ...
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1answer
141 views
Free body diagram and Newton's second law
Two bodies of mass $m_1=50 \text{kg}$ and $m_2 = 10 \text{kg}$ are
connected with a light rope through a pulley (no friction between the
rope and the pulley). $m_2$ moves on surface with angle ...
3
votes
2answers
81 views
Conservation of Linear Momentum at the point of collision
This is a pretty basic conceptual question about the conservation of linear momentum.
Consider an isolated system of 2 fixed-mass particles of masses $m_1$ and $m_2$ moving toward each other with ...
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2answers
56 views
effect of vertical collision on kinetic friction and subsequent change in horizontal velocity
Suppose somehow a block of mass $m$ is moving on ground, and the coefficient of kinetic friction between the block and the block is $\mu_k$. If I drop a tennis ball(of same mass) on it from a ...
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1answer
126 views
Is there a geometrical way to obtain a relationship between these vectors?
Suppose we have a setup like this. Here $a_1,a_2,b_1,b_2$ are acceleration magnitudes($b_1,b_2$ being relative) and $P,Q,R,S$ are not pulley/blocks but are points on the rope. If I use a geometrical ...
2
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2answers
130 views
Movement of man and ladder and their center of mass
Suppose there is a massless frictionless pulley.
A rope over it carries a mass $M$ and on other side carries a ladder of mass $(M-m)$ and a man on that ladder, of mass $m$. Now the man starts ...
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0answers
46 views
Does distance increase force at impact? [closed]
If a car that weights 1800 KG is traveling at 2.235 ms would it with greater force and 25 feet than 10 feet?
My calculations say it would be the same if the road was level and the same surface ...
1
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1answer
133 views
Work done by friction
Suppose we have a block of mass $M$ and we are moving it up a curve, very slowly ($a=0$). The surface is not smooth, and coefficient of friction is $\mu=\mu_s=\mu_k$.
To move the block we apply a ...
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0answers
49 views
Does the tension increase or decrease? [closed]
Trivial but answerable question here. As the angle increases, does the tension on A and on B decrease or increase?
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1answer
205 views
How to understand the work-energy theorem?
How to understand the work-energy theorem?
I took a short lecture on physics for engineering last week. The lecturer emphasized that the work done on an object will cause the kinetic energy change as ...
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1answer
71 views
Why work to change velocity from 0 to 20 km/h is less then from 20 to 40? [duplicate]
Imagine spaceship in vacuum with mass = 1. At beginning, it has velocity 0, and kinetic energy 0.
$$W_1 = 0$$
Then, it turns on its engine, and changes velocity from 0 to 20 (delta v = 20). It's ...
1
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1answer
157 views
Newton's Third Law of Motion
I want to start off by saying that I've looked around for other explanations, but I've not really found any satisfying ones. My question is basically the whole "Why can anything move at all?" ...
4
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1answer
151 views
Frictional force on a rope wrapped around a drum
So there's a rope wrapped around a circular drum, subtending an angle $\theta$. A large force, $T_A$, pulls in in one direction, and a much smaller force $T_B$ pulls in in another direction.
The ...
2
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1answer
71 views
Pendulum axes confusion
Suppose I have a simple pendulum and I want to calculate its acceleration when the bob reaches the maximal angle. I usually choose my axes such that the y-axis will be parallel to the rope. Then the ...
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1answer
96 views
Funny classroom experiments [closed]
I'd like to perform some weekly classroom experiments to keep my students interested and curious about everyday physics. Those experiments have to be quite easy to set up and not too easy to ...
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2answers
72 views
Kinetic energy with no velocity
When a body is displaced against the gravitational field of force it gains potential energy. When we drop the body it begins to move downward with a certain amount of acceleration, and the potential ...
0
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3answers
128 views
Force with zero acceleration [duplicate]
If I apply a force on a body which is kept against a wall, then the body will not move. The body is not moving means that its velocity is zero, and hence its acceleration is also zero. According to ...
