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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Question about levers

Suppose we have a lever $AB$ of length $1m$ and that the fixed point is $O$ and $AO=0,3m$. If in $B$ I have a down vertical force of $F_1=5N$, find the force $F_2$ applied in A that guarantees the ...
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3answers
337 views

If water is essentially incompressible, why are there tides?

So recently we were taught in school that tides are formed because the moon 'cancels out' some of the earth's gravity, and so the water rises because of the weaker force. But if water is not ...
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1answer
15 views

Why does the centrifugal term involve a vector originating from the center of Earth?

Why in every mechanics/dynamics book I look the centrifugal force due to Earth's rotation is measured from "the center of Earth"? For example in Marion's dynamics, the fixed inertial axes are placed ...
5
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3answers
380 views

Terminal velocity after vertical launch

If an object is launched directly up at its terminal velocity, will it have enough time/energy to reach its terminal velocity again before it hits the ground, or will drag prevent this? In this case, ...
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1answer
63 views

Why fall bombs always in a horizontal position?

I´m not sure but it seems to me when bombs are dropped they always fall in a horizontal position. Which is to say, not with their nose down. What´s the reason for this?
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What are the forces generated by a powered angle grinder?

I was wondering what forces come from a powered angle grinder. Given the fact that a angle grinder is not just a spinning disk, but also a grip containing the motor and mechanics i wanted to know how ...
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1answer
20 views

What is The force a body exerts on a vertical circular track?

I am trying to calculate the force a body exerts on a vertical circular track with no friction at its highest point I know the centripetal force at that point is mg and the given data is the velocity ...
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6answers
660 views

Why is the simple harmonic motion idealization inaccurate?

While in my physics classes, I've always heard that the simple harmonic motion formulas are inaccurate e.g. In a pendulum, we should use them only when the angles are small; in springs, only when the ...
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3answers
149 views

Does the work done by a person equal the work done on the object in this situation?

If you applied a constant force over a floor that has friction on an object, would the work done by the person equal to the work done on the object? Assume that the floor is flat and that the object ...
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2answers
70 views

Question about inertial mass and gravitational mass

I know that inertial mass $m_i$ is the quantity that appears in Newton's second law: $F=m_ia$ and that gravitational mass $m_{g_1}$ is the quantity that appears in Newton's gravitational law: ...
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0answers
27 views

Earth mass redistribution

Knowing we haven't imported construction materials from space has mankind altered the earth's weight through time due to building work? Or will it remain constant?
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2answers
48 views

Velocity of a body in a pulley problem involving a spring fixed to the ground

So the picture shows the whole situation. My question is, how do you find the velocity of the object after it had descended 10 cm (0.1 m) ? Pulley's radius 0.2 m, moment of inertia 0.2 kg/m I ...
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1answer
22 views

Confusion about projectile [on hold]

Yesterday i got a MCQ in exam that a body in projectile motion with initial velocity 20m/s creating an angle of 60 degree with horizontal. What is its velocity at max. Height (A) 10m/s Or ...
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0answers
14 views

What is the mass and velocity of an object lifted by helium balloons? [on hold]

If you were to lift an object with helium balloons, and the wind blew strongly enough to move the object and helium balloons, how would you work out the overall mass and velocity of them? I know that ...
4
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0answers
61 views

Find the relation between length of pulley and strings [on hold]

A pulley is pulled with external force $F$. $x$ and $y$ denote the displacement of two ends of strings of the pulley and $z$ is the displacement of the pulley. Prove That $$z = ...
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2answers
92 views

Matching Gravity with Centripetal Force

I was wondering if I'm correct in thinking that to determine the tangential velocity necessary to create the same gravitational force on a spaceship as on Earth you would use the formula ...
4
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1answer
171 views

Newton's Third Law As Discussed in Den Hartog's Mechanics

A question, but some preliminaries in order to avoid answers involving concepts not yet introduced in the text I'm reading--Den Hartog's Mechanics. Near the very beginning of his book, Den Hartog ...
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2answers
56 views

Which timestep should I use for a $N$-body simulation of the Solar system?

I am trying to implement a $N$-body simulation of the Solar system and I am stuck on the issue of the simulation timestep size. At first I would like to use a simple Euler stepping scheme. Knowing ...
50
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5answers
8k views

Why would a spinning space station create a centrifugal force on an astronaut rather than simply spinning around him/her?

We often see films with spinning space station that create artificial gravity by having the astronauts pulled outwards by centrifugal force. I'd like to know if this would really happen, and if so, ...
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1answer
37 views

normal force on a physical pendulum [duplicate]

I have read and understood that a normal force has got nothing to do with torque on a physical pendulum. But I can't understand in which direction the normal force points to. Can someone help? This ...
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0answers
18 views

Find the Work Done in this system [on hold]

In Inclined plane if friction force = the weight of the object. What is the total work done by this system?
8
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6answers
560 views

How can tangential acceleration from a radial force be explained?

A mass is attached to a rope, and put into a circular motion. If I pull the string from the center, the tangential speed of the mass will increase (by conservation of angular momentum). I am ...
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2answers
68 views

Proportional acceleration due to changing density of the Earth

My question has to to do with a recent video Minutephysics posted about the time it takes for a person to fall through the earth, found here http://www.youtube.com/watch?v=urQCmMiHKQk At around ...
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2answers
279 views

Intro Mechanics: Finding ball speeds after collision

So I'm reading about conservation of energy, momentum, balls colliding etc. and unsurprisingly there are hundreds of questions in my textbook where essentially they give me some of the variables (m1, ...
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5answers
6k views

How does a mobile phone vibrate without any external force?

How does a mobile phone vibrate without any external force? By Newton's law, any body can't move without any external force
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2answers
154 views

Infinite pulley system

http://www.physics.harvard.edu/uploads/files/undergrad/probweek/sol43.pdf Hi, I've been trying to solve this question for a while, I understand the first solution and also the solution to the second ...
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2answers
24 views

Centrifugal force acting on Spacecraft

This Question may sound very naive. Still somebody can explain the basics in simple words. As I understand, when we equate the centrifugal force acting on spacecraft in circular orbit with ...
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1answer
41 views

Impulse of two different objects

I was running over a question, A collision occurs between particles A and B which are moving in opposite directions in the same straight line. The impulse on each particle in the collision is 2N.s, ...
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0answers
65 views

Cavendish Experiment [closed]

Would the earth’s gravity overpower the gravity of the much smaller and less dense lead spheres?
32
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7answers
5k views

Supergun Launching of Satellites

I should say first that I don't believe this is a feasible launch method, otherwise NASA and other space agencies would be using it by now. It's based on this BBC news story Saddam Hussein's Supergun ...
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2answers
63 views

Force against mg when block is connected to block and held horizontally

In the image attached, what would be the force that would balance out the gravitational force $mg$? The block is also not accelerating downwards so there should be some force acting on the block to ...
5
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4answers
130 views

Rotating the bucket in circular motion without spilling water

In the bucket experiment when the bucket reaches the top of the circle why will it have a normal force acting on the water downwards? Doesn't normal force oppose any other force? There is no force ...
0
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1answer
25 views

A body acting by zero net external force

I wonder, for a rigid body, if the vector sum of all external forces acting on it equals zero (Fnet = 0), does it also leads to the vector sum of all external torques acting on it about any point ...
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1answer
40 views

Interaction Potential for Damped Driven Pendulum

I'm trying to use the velocity Verlet integrator to simulate a damped driven pendulum (with unit mass) described by $\ddot{\phi}+\gamma \dot{\phi}+\omega_0^2 sin\phi=Acos(\Omega t)$ The Verlet ...
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1answer
25 views

Mass is put on top of springs in series. Acceleration between springs? [on hold]

I am quite stuck with following problem: Two springs are in series. Let's call them spring 1 and spring 2. Spring 1 is connected to ground. Springs are connected with each other. Mass is added on top ...
3
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1answer
54 views

Collision between a “spring” and a particle

I am currently attempting to create a simple 2D physics engine, and I just need to know how to solve a certain collision. I have particles, and between any two particles, springs can be connected. ...
12
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3answers
1k views

Energy needed for Superman to take off and fly at the speed of sound

I just watched "Man of Steel", and I'm wondering if my logic is correct. Let's assume Superman is 80 kg. The energy required to take off from the rest to reach the speed of sound in air (if I neglect ...
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2answers
206 views

Would a planet in a binary star system follow Kepler's Laws?

I'm thinking it would not. I am thinking Kepler's Laws were a simplification that were possible with a simple two body (sun, planet) but would not apply for something more complex (sun1, sun2, ...
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0answers
19 views

Calculate Pendulum force [on hold]

I would like to calculate the impact force of a free fall 16kg Pendulum ball hitting the wall at 1.5m away. Please help. Thanks
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2answers
70 views

Newton's Cradle: why does it stay symmetric? [duplicate]

How is it that always the same number of balls leave at the other end in Newton's cradle. I understand that the momentum needs to be conserved, but as momentum is defined as p=m*v couldn't you have a ...
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1answer
282 views

Rotating platform with pulleys and stacked blocks

This was a practice test question. Consider the following figure. (If the frictional coefficients are unclear, between A and B we have $k_1 = 0.3$, B and platform is $k_2 = 0.2$. If you further ...
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1answer
20 views

External and internal resistance to airflow

If an aircraft was travelling at 100mph an hole was opened to allow 100mph into the cabin,then the airflow is feed into an amplifier like a ramjet and the airflow out of the ramjet was increased to ...
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1answer
62 views

Springs, elastic potential energy, kinetic energy

If a ball with some kinetic energy collides with a spring, the ball doesn't lose its kinetic energy in an instant, right? it loses kinetic energy as the spring gains potential elastic energy. Right? ...
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0answers
36 views

Pendulum acceleration vector [on hold]

I'll make this quick, I want the acceleration vector for a pendulum WITHOUT using angle acceleration and angle velocity, just using the tension and gravity forces. I tried to use the formula for the ...
-2
votes
1answer
29 views

Dropping a bolt in an accelerated lift [on hold]

Here's the problem given to me: A lift starts from rest with an acceleration of $a$. At the time it starts, a bolt is dropped from the top of the lift. If the height of the lift is $h$, find ...
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0answers
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6
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5answers
9k views

If a space ship accelerated constantly, would its astronauts constantly feel the forward movement?

I know that if a space ship suddenly traveled very fast, its astronauts would be fly against the back wall, potentially getting hurt. If the space ship suddenly stopped, they would also fly against ...
5
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3answers
692 views

Rocket launch from a mountain

If we were to build a high speed rail up the side of a mountain like in some Science Fiction movies, what is the velocity needed at the point of leaving the mountain excluding angular momentum from ...
1
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1answer
208 views

Can two bodies of different mass attached at ends of string passed over a frictionless pulley produce equal tension on both sides?

In my textbook there is given a case that to calculate acceleration and tension produced in string when string is attached at it's ends with two bodies of masses such that $m1>m2$ and the tension ...
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1answer
45 views

How can you find the impact necessary to change the direction of Earth's spin?

If an object the mass of the moon was to hit earth's surface at an angle that would be in the opposite direction of earth's spin, how can you find how much momentum the object needs to cause earth to ...