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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Variation in measurements of $g$ on the Earth's surface due to the Moon's gravity

A book, Exercises for the Feynman Lectures on Physics, has recently been published. It consists of homework problems to provide practice with the techniques and concepts used in the famous Feynman ...
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4answers
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Why do ships lean to the outside, but boats lean to the inside of a turn?

Small vessels generally lean into a turn, whereas big vessels lean out. Why do ships lean to the outside, but boats lean to the inside of a turn? For example, a boat leaning into a turn: ...
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1answer
58 views

Moment of inertia of a cylinder about its base

I've tried to find the moment of inertia of a cylinder rotating about an axis parallel to its base (i.e about the 'End diameter') as one can see here . But when I checked my results with different ...
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1answer
79 views

Geometry in diagonal matrix and inertia tensor

For this problem, can anyone explain to me why when $x_1$ axis is aligned with the diagonal of the cube, the resulting inertia tensor will become diagonal? How to interpret this result geometrically? ...
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3answers
66 views

Leading-order cause of diurnal (not semidiurnal) variations in $g$?

The following graph shows the result of a very impressive differential measurement of the gravitational field in Boulder, Colorado, over a period of a couple of days. Floris got it from a ...
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0answers
39 views

Birds inside of a closed box [duplicate]

Suppose there's a closed box with birds inside, on top of a scale. If the birds started flying inside, would the box get lighter?
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1answer
35 views

Calculating force of a car

I'm simulating car cruise system and my results are not making any sense. I have been told that my force formula is wrong but I don’t understand why it is wrong and how I can fix this. Does anybody ...
2
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2answers
65 views

Explanation for $M{\ddot{r}}=-\nabla \phi$

Could someone please explain this equation $$M\bf {\ddot{r}}=-\nabla \phi$$ Where $\bf r$ is a position vector and $\phi$ is the potential function. Could someone brief explain the potential function ...
2
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1answer
808 views

How is Mechanical advantage of Wedge = length of slope/width

Mechanical advantage is defined as Force Output/Force Input For a symmetrical wedge with the length of the slopes being equal and the width being the distance between the end points, articles quote ...
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3answers
642 views

How to determine direction of forces in a static problem?

I am consistently getting this wrong. To me, in the picture below, it would make sense that the structure would be pulling downward, and the cable BD would be pulling upward - thus the system is in ...
0
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2answers
36 views

Deriving spring oscilation period

We have a spring attached to a wall and at the other part an object on a frictionless surface. I tried to calculate the spring oscilation period. I used the conservation of energy and kinematics ...
0
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1answer
63 views

Questions related to resonance/standing-waves and sound

I understand resonance for a simple harmonic oscillator but not for more complex systems like standing waves. How can I be in resonance with the normal mode in an organ pipe? I understand that the ...
3
votes
1answer
63 views

Force to stop a moving rope vs. stagnation pressure of a fluid

Let $\lambda$ be a linear density of a rope which is moving into a scale at velocity v. The additional force on the scale due to the collision is given as $\frac{d p}{d t} = v\frac{d m}{d t} = ...
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1answer
60 views

Calculating the rate at which a car turns

This is going to be difficult to describe, as I have no real concept of this sort of physics, so please bear with me. If this is too much or beyond the scope of this website, I apologize. I am making ...
8
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2answers
1k views

How much more efficient is a road bike than a mountain bike? [on hold]

What would be a good estimate on the difference of efficiency between a road bike and a mountain bike? A number of links cite all the usual reasons: thinner tires, better aerodynamics... But I'm ...
2
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5answers
77 views

Doubt in collision

If a ball under the influence of gravity falls straight down from a height $h$, collides elastically with the floor, at the instant of collision, what forces does it experience? Shouldn't the ...
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1answer
35 views

Is Newtonian physics invariant under fast-forward?

I am aware of how the laws of physics are invariant with a time reversal transformation, so that (ignoring entropy) a film of billiard balls running backwards cannot be differentiated from one running ...
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2answers
35 views

Determinate the right force intensity given a certain amount of energy to spend

I am using Chipmunk's physics engine to simulate 2D classical mechanics of solid polygons (excellent by the way!). The only way you can alter the spontaneous behaviour of the the simulated objects is ...
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0answers
18 views

Mechanics Dynamics_Kinetics [on hold]

Figure shows an engine (e.g. IC engine, electric motor, turbine, etc.,) coupled to a load through a common shaft. The engine generates or supplies energy to the load, whereas the load absorbs the ...
4
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1answer
48 views

How to simulate rotational instability?

I'm trying to simulate (for an educational game) the well-known effect that rotating objects with three nonequal moments of inertia are unstable when rotated around the middle axis. Some explanations ...
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1answer
90 views

Feynman's derivation of Bernoulli (part of it)

OK, so what's up with the $\Delta M$ here? I don't get it. In fact, my textbook doesn't even put it in. I don't think it is a type-o because he continues on with the explanation. If anything I got ...
0
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1answer
52 views

Calculate orbit height from tangential velocity

Is it possible to calculate the altitude of a satellite orbiting a planet, just from the planet's mass and the satellite's velocity, assuming that the satellite is in a perfect circular orbit? If so, ...
0
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1answer
37 views

What indicates if object will be reflected - certain example

If I throw a small rock(1kg) at a big rock(100kg) the small rock is reflected; Let's say my weight is 80kg - if I would jump into a big rock instead of being reflected I would move in the same ...
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2answers
109 views

Why does moment of force depend on the perpendicular distance?

Couyld anyone explain how the lecturer concluded that $$(\underline{r_2} - \underline{r_1}) \times \underline{H} = \underline{p} \times \underline{H}$$
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2answers
24 views

Time of flight for a projectile with stated initial velocity and size at various distances

I've been mooching round the internet looking for an answer to this one and can't find a ready resource, hence the question. In short, I'm trying to discover the flight time of a shotgun pellet at ...
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6answers
5k views

How can the Earth keep spinning with a liquid core?

In regards to the 'conservation of angular momentum' being the explanation of why celestial objects spin... If you fill a ball or any other container with a liquid and try to spin it, you will not ...
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3answers
156 views

Confused about Newton's 3rd law

I am confused about Newton's 3rd Law. If a person jumps off the ground a force is applied both to the person and to the ground. However, as $F=ma$ acceleration experienced by the Earth is much less ...
2
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1answer
36 views

Lifting frictional force and relative values for kinetic vs static friction

My physics textbook says that friction mainly arises due to intermolecular attraction between atoms of the objects in contact and clashes between peaks are only significant for rough surfaces. I was ...
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1answer
54 views

Please explain these equations relating to Newtonian gravity [on hold]

Here is an extract from some badly-written slides: A planet in an orbit with radius $R$ having a period $T$ falls through a distance of $R$ in a time $T/4$. A planet has a speed of $R/T$ and an ...
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2answers
25 views

Work done by a frictional force on a cylinder

A cylinder of mass $m$ and radius $R$, is rolled on surface with coefficient of kinetic friction $\mu_{k}$ about the axis passing through the center and parallel to the surface, with initial ...
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5answers
3k views

How long must escape velocity be maintained?

Escape velocity from Earth's surface is 11.2 Kilometres/second How long would one need to maintain this escape velocity to actually escape Earth's gravitational pull? Must this 11.2 km/s velocity ...
2
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0answers
15 views

Equation describing the motion of an object attracted to magnet [on hold]

Imagine there is a strong magnet at (0, 0). There is a horizontal rail on y=1 on which a ferromagnetic object rides. The object ...
0
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4answers
56 views

A vehicle moves from rest to a certain distance. Would the distance time graph always be curved?

A vehicle moves from rest to a certain distance. Would the distance time graph always be curved ? Why cannot it be a straight line ? For example, a car moving from rest to 100m, with a constant ...
0
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0answers
22 views

How to find this torque? [on hold]

If I want to calculate the total torque, will it be $\sum$$\tau$$=$ $T_1$$l_1$$-$ $T_2$$l_2$$=$$I$$\alpha$ or $\sum$$\tau$$=$$T_1$$l_1$$-$$(T_2+mg)$$l_2$$=$$I$$\alpha$
0
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1answer
36 views

How to find the final momenta of these objects? [on hold]

Suppose two objects collide head on, where initially object 1 (mass $m_1$) is moving and object 2 (mass $m_2$) is stationary. Now assume that they have the same mass, so $m_1 = m_2$. Which ...
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4answers
2k views

The physical definition of work seems paradoxical

So this is possibly a misunderstanding of the meaning of work, but all the Physics texts, sites, and wiki that I've read don't clear this up for me: In the simplest case with the simplest statement, ...
2
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3answers
207 views

Can I make a rod in the vertical plane move with its one end on the ground in a slanting position?

Consider a rod kept vertically on the ground. I keeps the rod in a slanting position making some angle with the horizontal. Can I now move this rod along the horizontal plane by applying a force at ...
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1answer
80 views

Rotation and fictitious forces

A bug eats through an apple and forms a vertical, infinitesimally thin canal parallel to the vertical diameter at a distance $\frac{R}{2}$ from the center. The apple rotates at angular velocity around ...
2
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2answers
121 views

Bernoulli's principle on a curve ball

I've seen a few excellent answers here on the Magnus force, which explains why balls with a spin will curve. However, my intuition is still telling me that the Bernoulli's principle would push it the ...
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3answers
70 views

Projectile Motion with air Resistance - Adjust only the Angle to hit a target

OK, let me preface this by saying i am not a physics student, nor have i ever been. I am a software engineer working on a development degree. So this is homework but the assignment was just to create ...
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1answer
68 views

How do I describe and calculate the effect of an impacting object?

My lab studies the physiology of impact injury on biological tissues. I use a pneumatic cylinder to impart injury into a biological sample and then assess the molecular and physiological changes in ...
0
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4answers
63 views

If the velocity vector of a moving particle is always perpendicular to the position vector, is the path a circle?

A Newtonian physics question: If the velocity vector of a moving particle is always perpendicular to the position vector, is the only possible path a circle? What if the magnitude of the velocity ...
2
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4answers
69 views

Is work done by how much velocity is changed or how much displacement is done?

A sailboat is moving at a constant velocity. Is work being done by a net external force acting on the boat? The answer key is "No" according to the work energy theorem about work is done when ...
3
votes
1answer
189 views

Where is the “event horizon” on a basketball hoop?

I'm watching a lot of basketball this month. A common event is the ball going part way into the hoop and then coming out again. Announcers sometimes claim that the ball was "halfway through" when it ...
26
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4answers
4k views

Which ball touches the ground first?

This is a very well known problem, but I can't find an answer in the specific case I'm looking for. Let's consider two balls : Ball 1 weighs 10 kg Ball 2 weighs 1 kg Balls have identical volumes ...
0
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1answer
322 views

1D Kinematics - Relative Motion involving non-inertial frames of reference

I recently came across a question involving non-inertial frames of reference. I didn't quite understand the way it had been solved due to some conceptual confusion regarding certain deductions made to ...
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3answers
306 views

Physical plausibility of the Inverted Pyramid puzzle [closed]

The inverted pyramid puzzle has the following premises: A giant inverted steel pyramid is perfectly balanced on its point. Any movement of the pyramid will cause it to topple over. Underneath ...
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4answers
2k views

Why I think tension should be twice the force in a tug of war

I'm going to provide my argument for why I think the tension in a rope should be twice the force exerted on either side of it. First, let's consider a different example. Say, there is a person named ...
0
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2answers
74 views

What physical conditions would allow for this kind of perpetual seesaw

I'm working with a simulator(Box2D) and need to create these conditions. I have a perpetual seesaw with two objects on either side. I'd like for the following conditions to be met. The first ...
2
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1answer
298 views

Spring system - 3 DoF system and its properties while changing stiffness

I was given the attached 3 degree of freedom spring system with the purpose of analyzing it. I came up with the following equation of motion and then I ran Matlab to calculate the corresponding ...