# Tagged Questions

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.

55 views

### Simple Conservation of Energy Question

Deduce that the speed $V$ with which the bullet strikes the plasticine is about $160 \ m/s$ Using the conservation of energy, I equated the kinetic energy of the bullet to the potential energy of ...
37 views

### Animating Differential Equations

I was tasked with creating a $3D$ animation in Mathematica, which aims to describe the movement of a football through space as it's kicked. There are several differential equations regarding this ...
61 views

### Find the speed of a mass $m$ as it slides down a slope at an angle $θ$ starting from a vertical height $h$ using energy conservation [closed]

Note: The object starts from rest. I'm confused as to what formula for energy I should be using to solve this problem. Any ideas?
494 views

49 views

### Homework: Angular Acceleration from Net Torque [closed]

I have the correct answer but don't know how that is the correct one. My answers were way off which indicates I am missing something big but don't know what. Now the 4 torques are: t1=6.175, t2=....
41 views

### Collisions; Linear Momentum [on hold]

Let's say we got a rough surface with friction and there are 2 blocks, the block of the left has initial velocity and will collide with the block of the right, which is in rest. Consider an elastic ...
37 views

### Ratio between accelerations [closed]

I have worked on this problem on mechanics, but when I look at the answer to the problem I can't figure out why the acceleration of the block is twice the acceleration of the cylinder when the ...
21 views

### Cinematics; Equation of movement

What's the difference using the fórmulas v=d/t , or a=v/t, instead of equations of motion? I dont get it.
117 views

### Why are trains so hard to stop?

Since there are brakes on every car, shouldn't the stopping time of the entire train be the same as the stopping time of a single car? Is this because the cars themselves take a long time to stop, or ...
27 views

### Outbalancing vibrations

Consider a ship vibrating in the fundamental/principal/first symmetric mode shape (similar to that of a Bernoulli-Euler beam), induced by the main engine (similar to that of a vibration shaker). I ...
49 views

### System rigidity

What is the meaning of system rigidity in mechanics? I can't understand how to classify the system as rigid or not, and what is the effect of rigidity on the whole system. If you know anything about ...
107 views

### Physics of a sprint start

I am looking for an explanation to this illustration of a sprinter coming out of the blocks: Apparently, the production of horizontal force produces a great deal of body rotation (R1) which would ...
108 views

### Experimental data for asymmetric Newton cradle

Using a "successive impact model" (as if each ball were seperated from the other ones), I produced the following animations: You can see any combination of balls with masses of 1 or 2 (left) or 1 ...
101 views

### Can a particle pass through a point where wave function is zero?

Let's consider an infinite square well. In the first exited state there is a node at the middle of the well (i.e. wave function and thus probability of finding the particle is zero there). If I ...
29 views

### Work and energy example [duplicate]

The normal definition of Work, as far as I have read, is: Energy is transferred through work. But I just heard an educationist state this example, where there is a weightlifter who keeps up a huge ...
27 views

### A trio of spinning marbles

My little brother showed me this devised act in which he stuck three marbles in a triangular pattern When he spun any of those marbles, the triplet would first rotate normally, but moments later, ...
67 views

### Three connected balls

I'm stuck solving this problem with three small balls of masses $m$, $2 m$ and $3 m$ on a smooth table, connected by two equal, light inextensible strings as shown, and initially at the vertices of an ...
29 views

### Why does the inverse square law cause elliptical orbits? [duplicate]

I've seen it printed multiple places, here for example, that the reason orbits are elliptical is because the gravitational law has an inverse square of the radius. Why does this make the orbits ...
34 views

### Mathematical proof for elliptical orbit of planets [duplicate]

Elliptical orbits are stable for planets. But how to mathematically derive this result that a planet travels in an elliptical path? How are circular orbits less stable than elliptical orbits for ...
37 views

### Simplifying three mass, two springs system

I have a system of three equal masses connected by two equal string system. x_1 x_2 x_3 *--------*---------* ------> x M k M k M ...
49 views

### Conservative force for impulse analogous to conservative force for work done?

As force $F(x)$ can be conservative regarding work done between two points in space, can force $F(t)$ be conservative regarding impulse between two points in time?
39 views

### V-Belt: Torque on pulley and Max Tension

A V-belt consists of a driven pulley of diameter 250mm and a driver pulley of diam. 100mm , at a centre to centre distance of 170mm. the driver pulley rotates at 1440rpm, transmitting 30KW through ...
277 views

### How to solve this problem without using energy conservation

I believe most of you probably solved the following problem using energy conservation as shown here. It states a block of mass $m$ sliding on a sphere of radius $R$. I've be trying to solve this ...
58 views

### Why does overcoming inertia depend upon time?

When a paper over a glass is pulled suddenly, the coin over it falls to the water. But on pulling it slowly, the coin gets pulled along with the paper. Why does the coin in the former case not feel ...
64 views

### How to prepare mental skills to understand relativity theory? [closed]

Upto the high- school, I had to admit and write-on-exam the strange, counter-intuitive statements of relativity theory; those I could not believe. Now, I'm not a physics or math-student, (and indeed ...
44 views

### Notations used to express direction [closed]

We express direction relative to a reference point and call a certain direction positive and it's direct opposite direction negative, by convention. But, what notation should we use to express a ...
35 views

### Work done relation to potential energy

I know work done is negative of change in potential energy, I.e., $W=-(∆U)$. It means that Work done against a force (or work done on a system) increases its potential energy. And Work done by a ...
82 views

### If I throw or kick a ball, how much will the Earth move in the opposite direction?

I understand that for momentum to be conserved, if I throw a tennis ball (or kick a football) the Earth must move in the opposite direction to the ball. Obviously this is an infinitesimally small ...
119 views

### Is conservation of momentum and energy valid for non-inertial frames?

Conservation laws of momentum and energy are said to be the most basic principles of physics. Are they also valid for non-inertial frames, and in what way?
30 views

### Where does gravity get it's energy to cause tides? [duplicate]

The moon's orbital radius is fixed as a function of its velocity (I know it is actually drifting..). Since there is nothing in space to resist this velocity, it will continue orbiting "forever". Now ...
I'm not sure how to generalise Noether's theorem. For this L, I think $B\cdot\dot{x}$ is conserved so I tried to relate F and K to this and try to show that that was conserved but got no where. any ...
I'm making an app that times how long it takes a pebble to fall, then calculates the distance it fell. I noticed that the simple $f(t) = \frac{1}{2}gt^2$ was becoming increasingly inaccurate as the ...