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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Hole in Einstein's Theory of Relativity - Real or Perceived?

OK, so I am not a physicist, so go easy on me...I do really enjoy science though. I am actually a CPA by trade. So here is my question, what doesn't seem to add up to me about Einstein's theory of ...
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3answers
60 views

Forces and acceleration on rotating objects?

Suppose you have an object undergoing uniform circular motion, with force vector pointing towards the center and another force vector tangential. Can it be said that the net force pointing in the ...
14
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6answers
6k views

Can a car steer on a frictionless surface?

Do the front tires of a car act like gyroscopes, such that a car could steer on a frictionless surface?
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2answers
36 views

What happens to an orbiting body moving with the Earth's angular speed at various altitudes?

I was learning about inertial frames amongst other things, and I somehow came up with this question. Imagine we have a pole, made of imaginary very strong material that will never bend, placed at the ...
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3answers
42 views

How would filling a milk canister with helium affect the reading it makes on a scale?

Let's say that if I put a milk canister on a scale it shows 10kg. If I fill it with Helium it must necessarily be less than this, right? Can someone explain this (probably trivial) thing to me? :) ...
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16 views

Projectile motion with respect to integrating equation of motion [on hold]

Explain projectile motion with the help of "integrating equation of motion"
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3answers
77 views

Question of Conservation of Momentum

I think I understand the concept of conservation of momentum in an inelastic collision. However, what if two objects, one being more massive than the other, started out together and then separated ...
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1answer
66 views

Figuring out the time period of an Atwood system

SO I was working on Atwoods, when I came up with the following problem, It is more complicated but i should understand this simpler scenario first. As shown in the diagram above, (Atwood machine), ...
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2answers
193 views

Hourglass on the Moon

Someone asked me this, and I was surprised to find I couldn't answer it: suppose I have an hourglass / egg timer that times two minutes in Earth's gravity. If I used it on the Moon, how long would it ...
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3answers
304 views

If mass is added to a toy car does it affect its speed making it faster

If mass is added to a toy car (29.7g) and dropped down a wooden ramp would it affect its speed making it go faster? I know friction comes in to play to, so if you could give me an answer or an ...
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0answers
13 views

Postion of a cylinder rolling down an inclined plane [on hold]

I know that the acceleration of a uniform cylinder of known mass rolling down an inclined plane WITHOUT slipping with an inclination of $\theta$ is: $\frac23 g \sin\theta$. Suppose this term is called ...
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2answers
2k views

Slingshot Projectile motion calculation [on hold]

If I have distance the sling was dragged and the angle of the drag; then I require to calculate the projectile motion this sling shot would make. What are the equations that would enable this ...
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2answers
872 views

Elastic Collision And Momentum

The question I am working on is, "Two blocks are free to slide along the friction-less wooden track shown below. The block of mass $m_1 = 4.98~kg$ is released from the position shown, at height $h = ...
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0answers
190 views

Why the sum of energy don't increase in this device? [closed]

The black arm is turning clockwise at $w_1$. The red disk is turning at $w_2$ with $w_2 < w_1$. The disk is turning around itself counterclockwise at $w_2'=w_2-w_1$ in the arm frame reference. ...
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1answer
52 views

Will this sail-based moving system work? Why? [duplicate]

So simple: Will this sail-based moving system work? Why?
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6answers
720 views

Why does a conservative force return the work done against it by a body to that body?

Newton's 3rd law of motion: Newton's third law of motion or the law of action and reaction implies that there is no isolated force in nature. Whenever there is any force at all , there must be ...
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1answer
38 views

Why is it that friction apparently decreases with speed? [duplicate]

Whilst thinking of a trick where a magician pulls a tablecloth directly from under a full set dinner (a classic) I wondered why friction doesn't increase as speed does. I get that they use a pretty ...
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2answers
19 views

Understanding a graph of energy conservation with bounded and unbounded motions?

This graph is from the physics undergraduate text "Classical Mechanics by Douglas Gregory". Above this graph was the statement: What I didn't understand is- as stated in the under [*paragraph], ...
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1answer
106 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
56 views

Pushing over a block [on hold]

Consider a rectangular block of mass $m$ and uniform density resting on a frictionless surface. The height is $h$, the width $w$, the length $l$. Consider one of the faces with dimmensions $l$ by $h$. ...
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1answer
47 views

Big jump or small jumps?

To travel a certain distance s, is it more energy efficient to use one massive jump, or several small jumps? (First approach deleted, didn't make sense) This approach is probably a lot better. ...
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4answers
749 views

Newton's third law.. please explain here

According to Newton's third law, the force acting on object is equal and opposite to the other object that is applying the force. If I push a table with 5N force then table is doing the same. But the ...
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1answer
44 views

How would we find what sort of a force this one is? [closed]

The potential energy for a force field is given by $U = -Kxy$, where $K$ is a constant. The body moves in an $x$-$y$ plane. Find the force vector. $i$ is the unit vector along the $x$ axis, $j$ is ...
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2answers
93 views

Is the Fundamental Theorem of Calculus really applicable to the definition of work?

When the force $F$ on an object is not constant, then the work it performs is defined as $$W = \int_{x_0}^{x} F(X)dX.$$ Now, the Fundamental Theorem of Calculus states that $$\text{If}\,\,\, f(x) ...
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0answers
25 views

Weight of a hemispherical bowl and a mass $m$ [on hold]

A particle of mass $m$ is A hemispherical bowl of mass M rests on a weighing scale. The inside surface of the bowl in frictionless. A particle of mass m is released from rest at the top of the bowl ...
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2answers
74 views

Finding sphere of influence in multibody system

I would like to draw a boundary illustrating the sphere of influence of each body in a 3 body system. What is the best way to find such a boundary? My understanding is at the edge an SoI is the ...
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3answers
279 views

Is the Normal force dependent on the density of the object the body is resting on?

If a body is resting on the ground, the Normal force equals its weight. If I keep putting another body on top of it, eventually the body will start moving into the ground until the new Normal equals ...
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1answer
64 views

Can a body ever experience acceleration this strong?

Using the Schwarzschild radius formula, I approximated the Sun's Schwarzschild radius to be $3\text{ km}$. Now assuming I have a body (not a human body) which is at a distance of $10\text{ km}$ from ...
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5answers
427 views

Force required to drive car

From what I know of Newtonian Mechanics, if an object is moving at a constant velocity, the net force acting on that object is equal to zero. If there is friction, then the applied force required to ...
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1answer
179 views

Does a rotating plank only acquire rotational kinetic energy?

I have another doubt with a Kleppner problem :(. A thin plank of mass M and length l is pivoted at one end. The plank is released at 60$^{\circ}$ from the vertical. What is the magnitude and ...
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0answers
20 views

What are the factors involved to survive an eleven story free fall? [on hold]

http://abcnews.go.com/US/wireStory/window-washer-falls-car-san-francisco-27099646 Am I the only one that thinks one could write an entire thesis on this subject?
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2answers
118 views

“Skidding” to Brake on a Skateboard

When people are skateboarding, sometimes they kind of push out their back foot when they turn while carving, causing the board to skid a bit. I was wondering the physics behind this, any details on ...
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0answers
48 views

Help with my schoolwork [on hold]

I have to do project about Newton's Movement Laws, and I decided to write about the situations, where do NML not work. For example, why does photon have force and momentum, when it has 0 mass. It's ...
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3answers
454 views

Can we explain Newton's first law mathematically?

At constant speed there is no acceleration. (f'(x)=v'=0=a) .If a=0 then F=ma=0 and therefore no force acts on the object so the object will continue in the same ...
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3answers
208 views

Elastic collision of point particle and rod

A 1 meter long rod on the ice with mass $m_2=1$ kg is perpendicularly hit on one end by a point particle with mass $m_1=0.1$ kg. The collision is elastic and the point particle is bounced back in ...
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2answers
539 views

Why don't we consider centrifugal force on a mass placed on earth?

Let us say a block of mass is placed on the surface of earth. Then while drawing the forces on that body, we say: Force $F = mg$ acting towards the center of Earth. Normal reaction $N$ offered by ...
-1
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1answer
30 views

Find the impulse momentum [on hold]

A boy of weight 40 kg stands on a board of weight 60 kg. The board is on ice (friction force =0): Find the velocity of the movement of the boy and the board when he moves from one side to another.
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4answers
437 views

Does Newton's third law apply to momentum or to forces?

I read all the previous answers concerning the 3rd law and I have seen that it is definitely not universal, (Edit: but conservation of momentum is. If it is not universal it should be not a problem to ...
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2answers
58 views

What if the centripetal force were acting outward?

Centripetal force is the centre-seeking force & is responsible for circular motion. But what if the centripetal force were acting radially outward? What would happen then?
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7answers
4k views

“Falling upward” - how far you have to be from Earth to start falling to the Moon?

Talking about gravity with my 9 y/o she asked when do we start "falling upward" to the Moon. What is the distance at which the Moon's gravitational attraction is higher than that of the Earth and thus ...
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2answers
30 views

Pendulum in Accelerating Elevator

I have been looking for this for quite some time now. A simple pendulum behaves in SHM. Let's put that pendulum in an upward accelerating elevator. The component of the force that acts in SHM ...
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1answer
36 views

Mathematical misunderstanding of Work-Potential Energy Theorem?

This is a relatively basic question, but I don't understand why it is the case. This is from my dynamics book and is mainly a mathematical misunderstanding. $$ \ dU = F\cos\theta ds $$ Which means ...
4
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1answer
243 views

If friction disregard area, why the direction you drag a long object matters?

I am talking here about dry friction between solid objects, for example a ruler and a table, not anything lubricated or fluid. I noticed that with a ruler and a table for example, if you drag the ...
0
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1answer
25 views

Finding acceleration only with known acceleration distance, final velocity, and mass for Newton's Third Law [on hold]

So I have this problem that I am trying to figure out. I need to find the acceleration of a 4 kg object, that is accelerated through a distance of 1 m to the left to a final velocity of 6 m/s. This ...
5
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5answers
352 views

Kinetic energy vs. momentum?

As simple as this question might seem, I failed to intuitively answer it. Let's assume there is a $10,000$ $kg$ truck moving at $1$ $m/s$, so its momentum and KE are: $p=10,000$ $kg.m/s$ and ...
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4answers
70 views

Centripetal force for non-uniform circular motion

For uniform circular motion, centripetal force is given by $$\dfrac{mv^2}{r}.$$ But what will be the centripetal force if the circular motion is non-uniform in the sense that linear velocity is ...
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1answer
119 views

Does a pivot exert an additional force, normal to the centripetal force, on an object rotating about it?

A thin plank of mass $M$ and length $l$ is pivoted at one end. The plank is released at 60$^{\circ}$ from the vertical. What is the magnitude and direction of the force on the pivot when the plank ...
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0answers
17 views

Suspended mass in motion free-body diagram [closed]

A 20kg mass is held by two ropes which span 90 from each other. The mass is being accelerated at 1m/s^2 to the right. Draw a free body diagram for the mass and find the numerical values for each ...
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2answers
42 views

Is there a normal force on an object submerged in water?

I am not sure about whether or not there is a normal force acting on an object submerged in water. It might be because I have not good understanding about what a normal force actually is. I know a ...
0
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1answer
994 views

Force acting on a simple rigid body in space

so this is the question that's been bothering me: Say you have a simple rigid body in space that is at rest or travelling with only translational motion at a constant speed. Say that the body is ...