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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What is the use of orthogonal curvilinear co-ordinate system?

Orthogonal curvilinear coordinate system is made of intersecting sets of confocal ellipses & hyperbolas. But, I have found no book that would describe this how to use this coordinate system ...
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Can center of mass move without any force?

For instance, consider a weight on one end of the ring. Assume that the ring has negligible mass compared to the weight. When the weight splits into two, moves around the ring and recombines at the ...
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77 views

An interesting problem on springs [closed]

If I place two identical objects of mass $m$ at either end of a spring with spring constant $k$ and the whole system is placed on a horizontal frictionless surface, then what is the frequency of ...
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49 views

Very confused about effective spring constant

I know that for springs in parallel, the effective spring constant is $k_1+k_2$ and for springs in series the constant is $1/(1/k_1+1/k_2)$. But there are some weird problems where finding the ...
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1answer
53 views

Tipping over objects on a frictionless surface

Is there any way you can topple over a rod which is standing up on a frictionless surface?
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54 views

Where does energy goes if I jump down from a balloon?

Suppose you are in a hot air balloon of mass $M$ which is floating in the air, and you get out and start climbing down a rope at constant velocity $v$. By conservation of momentum we can show that the ...
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45 views

Linear Gravity Inside Solid Sphere Derivation

I am currently taking a dynamics module at university and am revising for a midterm exam. One of the problems on a past paper was to consider a mass falling through a hole in the Earth (pole to ...
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3answers
60 views

How to explain that an object at a certain point with zero velocity can move away from that point by having an acceleration?

As A.P.French points out: You may feel, . . . , that we have gone to excessive lengths in our discussion of instantaneous velocity & acceleration. But make no mistake about it; these are very ...
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71 views

Clearing up confusion about orbital mechanics

When I see an orbital mechanics problem, I recall the following things from my "toolbox": Angular momentum is conserved for a body orbiting a planet, since the torque due to gravity is 0. Kinetic ...
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1answer
78 views

Springs at an angle [closed]

I'm trying to find the equation of motion for the following system: This is how I proceeded: Let's call the length of the hypotenuse $s$. Then, $$F = 2 \sin{\theta}\cdot-k(s - l_o) = -2kx ...
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1answer
38 views

If a place a spring in a box and drop the box, what happens?

Suppose I a holding a box in my hands, and inside the box a spring with some mass attached hangs from the cieling of the box. Initial the system is at equilibrium, then I let go of the box and it ...
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1answer
33 views

Placing an object in a tub changes the weight of the tub?

Suppose you have a tub filled with water and it rests on a scale so you can measure the weight. If you place an object in the tub, will the reading on the scale change? Clearly if the object sinks ...
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1answer
98 views

Can we make a “Gravity Mill” based on principle(s) of Newton's cradle?

DISCLAIMER: Newbie/Wannabe Physicist. What's to stop us from making a "Gravity Mill" which is a bar/rod attached with weights on both ends and pivoted at the ...
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1answer
93 views

The velocity of the flowing coming out of the balloons?

Last day , when i was working on two interconnected balloons , a question was kicking my brains !!! This is the explanation of the question: First , suppose a system that composed of two spherical ...
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2answers
65 views

Acceleration of ball rolling down incline

Suppose you have some object (which can roll like a ball,cylinder,wheel,etc) rolling down an incline without slipping (moment of intertia $I=kmr^2$. I want to find the accleration of the ball as it ...
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3answers
791 views

Why don't we consider jerk in physics classes? [duplicate]

When i got more into physics, i started asking myself if just like acceleration represents the growth of speed, something else could also represent the growth of acceleration itself. And it came that ...
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1answer
26 views

Acceleration in a system equal for every body — why?

A 1 kg cart can slide frictionlessly on the table. The black weights each weigh 1 kg. The pulleys are frictionless. The task is to determine the acceleration of the cart. For the left-most ...
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63 views

Why golf balls travel faster if they spin?

From the book I have been given to read I found that balls spin due to the centripetal force but i am confused about how exactly do the resultant force causes it to spin and move forward about the ...
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0answers
19 views

Is the moment-curvature relation for an elastic beam general?

The relationship between the moment and the curvature for an elastic beam is $$M = -EI\kappa$$ Previously, I have only used this with small deflections in static calculations. I am currently working ...
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20 views

Would cereal still group together if it were suspended in the liquid (milk) - rather than floating on top?

According to my interpretation of several online sources (correct me if I am wrong), cereal tends to group together in our bowls of milk because it creates a deformation on the surface of the liquid ...
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1answer
57 views

newton's cradle with 2 balls dropped from same height at same time

I'm creating a logo and want it to be as exact as possible. The logo idea is a "Newtonian cradle", but with only 2 balls and on straight steel wire (can't be bend). What would happen if I dropped ...
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1answer
42 views

Newton's 2nd and 3rd Law clarification [duplicate]

Hi I have a quick question. I know this may be a common question. If N3L states that there's an equal and opposite force, why do things still move? I have read up a lot and this is my understanding. ...
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83 views

Why isn't jerk necessary?

I've recently thought about the rate of change in acceleration and found out that is exists and is called jerk. I've looked at some questions and answers but i could not understand something in this ...
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42 views

Are velocity and acceleration the fundamental quantities to use physics? [duplicate]

This question may seem out of the box, but i'd like to ask it since I thought about it today. Every time i had physics classes, when the subjects was mechanics, speed and acceleration along with ...
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6answers
977 views

Elevator cabin problem

The following passage is extracted from the book "Concepts of Physics, Part 1" by H C Verma: Let us consider the situation shown in figure. An elevator cabin falls down after the cable breaks. ...
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1answer
75 views

Why doesn't air below a falling object balance its weight? [duplicate]

Consider the following scenario: a body is dropped and it hits the air molecules below it with a force equal to it's weight. By Newton's third law, the air molecules below should exert the same force ...
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1answer
45 views

Stagnation Point around Sharp Corner

I am trying to design a water-channel that travels through a metal block shaped like a square to cool it down (so it is a 2D problem). One consideration is the wetted surface area, which allows more ...
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3answers
131 views

Why are forces independent from the frame of reference?

The following question occurred to me while reading a proof of the following statement: If K is an inertial frame of reference, then a K’ frame of reference, which is moving with a constant ...
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1answer
98 views

Using Lagrangian mechanics instead of Newtonian mechanics

When studying advanced classical mechanics, we all study about Lagrangians and the Euler-Lagrange equations and their importance. Of course, the Lagrangian is calculated based on the potential and ...
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1answer
12 views

Two-linkage under the force and friction

I need to find friction force in this configuration. Book says that $F_{fr}=\mu P.$ but i think that force $P$ is distributes evenly between hinge (A) and sliding block (B), so friction must be $1/2 ...
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3answers
59 views

Newton's Second law of Rotation

In my book (Halliday Resnick Walker) there is a solved example which is as follows There is a uniform disk with mass $M$ = 2.5kg and radius $R$ = 20cm, mounted on a fixed horizontal axle. A block ...
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2answers
241 views

Is it possible to determine the outcome of any impact knowing only the ratio of masses? [duplicate]

In elastic collisions in 2-D if two balls $A$, $B$ ($m_A = m_B$, $R = 1$) have equal mass we can determine in advance the outcome of the collision. If cue-ball $A$ impacts object-ball $B$ (at rest) ...
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0answers
51 views

How can we theoretically calculate the number of balloons needed to stop a bullet?

After watching this video, I am interested in proving it mathematically. The problem is that how can we apply the conservation of momentum here to find the velocity of the bullet while we don't know ...
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2answers
68 views

Why does General Relativity predict more light deflection than Netwonian Physics?

If one looks at the limit as light's mass approaches zero, Newtonian Physics predicts a deflection of light (this can be seen by the fact that all objects are accelerate the same due to gravity.) ...
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66 views

Polar moment of inertia of a cylinder

So I know the polar moment of inertia of a solid cylinder is: $$ I= \frac{1}{2} mr^2 $$ My question arises with the polar moment of inertia uses for solid cylinders in my mechanics of materials book, ...
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1answer
365 views

Bowling Ball Sinking Rate - Variable or Constant?

In today's (Jan. 16, 2014) xkcd What If?, Randall Munroe discusses how fast a bowling ball will sink to the bottom of the Mariana Trench. He calculates the drag on the ball, and then plugging in the ...
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1answer
94 views

Solving the Kepler problem

I'm trying to solve the Kepler problem using the Lagrangian, $$L = \frac{1}{2} m (\dot{r}^2 + r^2 \dot{\phi}^2) - U(r) $$ which after quite a bit of fiddling with, by noting that the angular ...
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0answers
37 views

Relative velocity between a ball hitting a rod [closed]

A ball of mass $m$ travelling with a velocity $v_0$ collides elastically, and perpendicularly with a rod at a distance $d$ from the center of the rod. The rod has a mass $M$ and lies on a frictionless ...
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1answer
104 views

Conservation of angular momentum in a free rod

When a collision is elastic and no external torque acts on a system, angular momentum is conserved I found this example and checked the results: A ball (m = 1 Kg , v = p =+22 m/s, Lm = +11, Ke = 242 ...
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22 views

Obtaining angular velocity of a general orbit

Provided you are given a effective potential function i.e. $$ V_{eff}=\dfrac{J^2}{2ml^2sin^2(\theta)} + mgl(1-cos(\theta))$$ how do you obtain the angular velocity for different types of orbits; i.e. ...
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1answer
153 views

Shouldn't motion be represented as a Taylor series rather than a finite sum of functions or a polynomial? [closed]

Since the change in velocity of an object at rest prior to time $t_{0}$ implies a change in acceleration — that is, let's postulate, $ \mathbb{P} $, the object would have remained still, so there was ...
3
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3answers
1k views

How hard would I hit the ground on Mars?

How do you calculate with how much force a mass would hit the ground when falling from a certain height? In particular, I'm curious to know how the force of impact on Earth compares with Mars, so ...
4
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2answers
106 views

Why do your fingers alternate then meet at the center of mass of the object?

Hold a pen (or pencil, ruler etc.) using your two index fingers with your fingers at the ends of the object. Now move your two fingers toward each other. Assuming the frictional force provided by both ...
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1answer
29 views

Period of oscillation with time independent factor

How can you determine the period of oscillation from a mass that is suspended from the ceiling? The equation becomes: ${{d^2x}\over dt^2}+kx-mg=0$. I am confused by the constant $mg$, because in the ...
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2answers
511 views

What will be the equation of motion of driven pendulum for amplitudes beyond the small angle approximation?

When finding the period of a pendulum beyond the small angle approximation, we have to use integration for small interval of $\theta$ and elliptical integration. I was trying to apply this situation ...
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1answer
65 views

Find center of mass and moment applied on beam structure [closed]

I have a simple physics problem to solve but it is giving me a slightly difficult time to figure out. The problem: I have a beam structure with same cross section. It consists of three beam. First ...
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0answers
48 views

Instantaneous acceleration in non uniform circular motion

How is instantaneous acceleration different from tangential acceleration in a non uniform circular motion? We know that instantaneous acceleration is tangent to a point at any given time and so is ...
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3answers
65 views

Why does reduced mass help when talking about two body problems?

I hear people say that reduced mass, $\mu$, is used for two body problems, but what sort of problems? Is it so that the two body system can be treated as one body or is it to simplify calculations ...
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1answer
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Momentum and Kinetic Energy Conservation in Inelastic Collision

Let a ball fall freely to the ground, hit and bounce back. Assume mass of the ball does not change during this. Since momentum is conserved in all collisions, $p_i = p_f$ In this example, the system ...
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5answers
156 views

As a car turns around a circle, why does the force of static friction point towards the center of the circle [duplicate]

A car moves along a flat, circular road. It has a tangential velocity to the road, but the car tires change direction and the car experiences a force of static friction causing a centripetal ...