# Questions tagged [newtonian-mechanics]

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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### When a ball on a rope swings in a circle, is there both centripetal force and tension force?

I'm learning about centripetal force and I was shown a scenario where a man was spinning a rope attached to a ball over his head. There's a centripetal acceleration toward the center and therefore a ...
3answers
58 views

### Newton's law of motion for extended objects

I read somewhere that Newton's laws may be used even if the object under consideration is an extended body, provided each part of this body has same acceleration. Does that mean that if i have a ...
1answer
15 views

### System losing energy in a cold room

A system (eg. below), that constanty loses energy (ie. as heat due to friction) is kept in a cold room, will it lose energy faster compared the same system in a warmer/room temperature environment? ...
1answer
50 views

### Different forces from different inertial frames?

I've been having trouble understanding this equation here derived in the picture given below. If I change reference frames to one which is moving at a velocity u with respect to the first frame, then ...
1answer
151 views

### The physics of why 3-wheeled cars are not effective

A century ago, 3-wheeled cars were quite popular, like the Morgan below. $\hskip2in$ The sale of these cars has been banned later (until recently) in many places due to the associated safety ...
2answers
78 views

### Why is $\theta=\beta/2?$ - Kinematics [closed]

An aircraft is flying horizontally in a circle of radius $b$ with constant speed $u$ at an altitude $h$. A radar tracking unit is located at $C$. Write expressions for the components of the ...
2answers
60 views

### Question related to maximum static friction and minimum $\mu_s$

I think I have the right formulas the answer the following question, but there is something conceptual that is throwing me off (see end of question). A body with mass $m$ is located on a slope with ...
1answer
45 views

### Interaction between various forces, by which one is to calculate an angle? [closed]

I am new to Newtonian mechanics, and was wondering about the following question. I basically have the ingredients for the answer, but I cannot seem to find the way to put this together into one ...
1answer
42 views

### Fictitious forces in relation to normal force

I am new to Newtonian mechanics, and was wondering regarding the following: The system pictured below is moving at acceleration $a$ towards the left. The mass of the ball is $m$, and there is no ...
4answers
31 views

### Is work equal to area between graph and $x$-axis in a graph of force vs displacement?

Is this true even when displacement is not in direction of force? $$W = \int (F\cos\theta)\text dx$$ and area is $\int F \text dx$. In my book that area is given as one of the definitions ...
1answer
24 views

### An object having a general plane motion exerting force on air

assume that we have ball that's both spinning and moving in a straight path through the air. Does the ball exert a force at right angles to the path it's moving on the air? If the answer is yes, ...
0answers
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### How do they equate a scalar quantity and a vector quantity? What are the factors depend on $\vec F_{R,L}$?

Link to video He said that Tension is a magnitude of the force acting from the left piece to right or force acting from the right piece to left (i.e. $|\vec{F}_{R,L}|=|\vec{F}_{R,L}|=T(p)$. So, ...
1answer
20 views

### Freefall equations and forces

Consider a scenario where a 100kg mass is hanging from a rope. It's stationary, so the force it exerts on the rope is given by $F=ma$, where $a$ is the acceleration due to gravity, which works out to ...
4answers
83 views

### Why is it okay to decompose forces?

I guess the title says it all, it doesn't seem intuitive that we can consider something as abstract as forces to be decomposable vectors. An example would be a mass sliding off an inclined plane, we ...
1answer
60 views

### Why is the Earth not an inertial frame of reference?

From many sources I have found the explanation that the Earth is not an inertial frame of reference because it rotates around its axis. However, nobody mentions the rotation about the Sun. What I ...
2answers
34 views

### Uniform Circular Motion vs Change in speed of $x$ & $y$ Components

If you are moving at a set rotational speed the x,y components are constantly accelerating and decelerating (aka simple harmonic motion), this is obvious in order to travel in a circular path. My ...
2answers
53 views

### Compress a Spring without Moving It? [closed]

So after putting in some research effort into the math, it seems like this should be possible under the right criteria. Say I have a spring with a mass of 1500kg and a spring constant of 100N/cm and ...
2answers
65 views

### How can I measure the strength of a wrist gripper?

I've been given a hand gripper and I want to test its strength in $kg$. Of course, I could compare it to grippers with known strengths or grip it to the maximum and apply the same force on a bathroom ...
1answer
41 views

### Why is the tension $\vec T$ downwards in the system?

Link to video Doubt: At pulley $A$, consider the free-body diagram. Why is the tension, $\vec{T}$, in both hands downwards? I know $\vec{T}_2$ is upwards since it is the force acting upwards in ...
0answers
33 views

### Is it possible to model a locomotive capable of going 0-60 in 60 secs with $\sum F=F_{engine}+\mu_{rolling}mgv$?

The problem of just considering engine force and rolling friction $$\sum F=ma=F_{engine}+\mu_{rolling}mgv$$ is that when you solve for velocity like $$\dot v=\frac Fm-\mu gv$$ with initial ...
1answer
75 views

### An exploding projectile [closed]

A mass $3m$ is thrown with a velocity of $20\sqrt3$ m/s at an angle of $30^{\circ}$ to the horizontal from a point, say $A$, on level ground. After reaching a certain height, $h$, it explodes into two ...
2answers
139 views

### Gravity as a force [closed]

I want to know if my reasoning is correct. If you drop an object at a height, the object accelerates downward at a constant rate due to gravity. Because we defined force as the ability to accelerate ...
1answer
48 views

### Why is there energy being spent / work being done in a static system?

Sorry that I don't have pictures. Imagine I have a steel circle, like a hula hoop. On opposite sides of that circle I attach two springs, then stretch them. They meet in center where I hook them ...
0answers
95 views

### A concise definition of a frame of reference in Newtonian mechanics?

I've read Wikipedia's entry on frame of reference and also followed all of the references cited in the text (Salençon, Brillouin, Norton, etc) but I'm struggling to find any concise definition in all ...
0answers
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### How would one calculate velocity with respect to time in Case 2?

Case 1. : The rocket is weightless in space. It's fueled with propellant. It's wet mass is starting mass $m_s$ and dry mass final mass $m_f$. Suppose rocket's initial velociti is 0. The rocket ignites ...
2answers
41 views

### Static friction in a slope and two boxes problem

The context: Calculate the string tension in the situation where two boxes are stacked on a slope and moving with uniform velocity, given that the kinetic friction coefficient between the heavier (...
1answer
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### Definition of non-conservative force [duplicate]

In defining conservative force, we say that "The potential energy difference is path independent." However, as far as I understand, potential energy only exists when there is a force field. ...
1answer
35 views

### Can you please explain the statement in the David Morin's Classical Mechanics? [duplicate]

For example, in a hanging massless rope, or in a massless rope hanging over a frictionless pulley, the tension must be the same at all points, because otherwise there would be a net force on at ...
1answer
24 views

### The sign of $d\mathbf{r}$ when integrating the universal gravitational force in order to define gravitational potential energy [duplicate]

I am trying to find gravitational potential energy by integrating the gravitational force: $$\mathbf{F}(\mathbf{r}) = - \ G \frac{Mm}{|\mathbf{r}|^2} \ \hat{\mathbf{r}}$$ where $\mathbf{r}$ is the ...
7answers
248 views

### Why normal reaction, tension, and friction forces are reference frame-independent? [closed]

I can not provide a whole manuscript of examples where I can justify that these forces are reference independent. I don't think that there is any such case where these forces are reference-dependent. ...
2answers
95 views

### Chain slipping off a sphere - Mechanics problem

A uniform flexible chain of length l rests on a fixed smooth sphere of radius R such that one end A of the chain is at top of the sphere while the other end B is hanging freely. The chain is held ...
0answers
26 views

### How does particle size affect the elasticity of a collision between two particles?

Lets say two particles in an aerosol collide. How does the size of the particles help determine if the collision is elastic or inelastic? I am specifically referring to the following quote. It ...
0answers
10 views

### Relationship between angle of repose and critical angle

Is there any numerical relationship between the angle of repose and the critical angle of a sandpile?
2answers
64 views

### Vertical component of friction

If we have a car of mass $m$ sliding around a banked curve of angle $\phi$ with some coefficent of friction ${\mu}$, then the normal force will be $$Ncos\phi= mg + {\mu}F_{g}\sin\phi$$ But this ...
2answers
58 views

### Flight time of spherical bullet fired horizontally versus dropped vertically / effect of crosswind on spherical car

Would a spherical bullet fired horizontally from a musket stay aloft longer than a spherical bullet dropped from the same height? I know two similar questions have been asked (Will a bullet dropped ...
1answer
90 views

### How to find acceleration given the function of the path taken by an object? [closed]

I'm attempting to find how much force a car will experience during cornering. I understand the acceleration acting on the car if it were travelling in a circular path would be $a = v^2/r$. However, ...
1answer
20 views

### Pressure Difference after Throttle/Orifice

I am helping a student with her exams, but since I have a little to no idea regarding fluid dynamics, I would like to ask here about a force. Consider the system of the following figure The goal is ...
1answer
39 views

### Does asymmetric rigid body experience torque-free precession?

I know that a top (or any axis symmetric body) experience torque-free precession. and I know that asymmetric body, with 3 different dimensions has stable rotation when the angular velocity is near the ...
5answers
528 views

### Do objects besides strings, ropes, and rods have tension?

Why do we define tension only in strings and ropes and rods and such? Shouldn't every object experience tension force? Like when you pull a paper from opposite sides, it gets taut, and experiences ...
1answer
85 views

### How to prevent an asteroid from spinning while pushing it?

Consider a perfectly spherical asteroid in deep space (away from other celestial bodies). The asteroid has uniform density so its Center of Mass (CoM) coincides with its geometric center. The ...
1answer
36 views

### Tension in a ring rotating about its own axis

A ring of mass m and radius R is placed on a smooth horizontal table and is set rotating about its own axis in such a way that each part of the ring moves with a speed v. What is the tension in the ...
1answer
32 views

### Tensions in objects other than ropes

Can you have tensions in objects other than strings and rope? suppose you have a piece of paper and you pull at it from both ends it becomes sort of taut similar to how a rope does when you pull at ...
3answers
56 views

### Equilibrium of a body in torque problem

I was watching a video about torque in which the task was to find the force $F_2$ when a body is in equilibrium. The person in the video said that in order for the body to be in equilibrium, two ...
1answer
65 views

### Calculating moments of inertia for partially filled cylinders [closed]

I'm planning on doing an experiment with cylinders of equal length and constant density but different solid fills. For example, a filled cylinder, $75\%$ filled, $50\%$ filled, $25\%$ filled, and a ...
4answers
238 views

### U-turn in Deep Space

While writing a physically realistic game ( "Asteroid Defender" ) a physical question came up whether Diag.1 or Diag.2 or Diag.3, correctly depicts reality. In deep space (away from other celestial ...
2answers
27 views

### Simple harmonic motion on a vertical spring

Say we have a spring attached vertically to a wall. Now, let's assume that we attach a mass to the spring, but we do not let the spring extend just yet (we could hold the mass on our palm for example)....
1answer
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### Help with the problem of moving two fingers along a yardstick

The following problem is taken from an MIT homework assignment: Hold a yardstick horizontally on your index fingers and slide your fingers together smoothly. The stick slides first on one finger, ...
2answers
53 views

### Time to move along a path?

Let's say I have an arbitrary path from point $A$ to point $B$. A particle moves from $A$ to $B$ under the influence of gravity but also impeded by a frictional force $\vec{F_\mu}$. The gravitational ...
1answer
63 views

### Mechanics of a particle problem (potential energy vs. work approach)

I'm trying to reconcile two methods of approaching a problem, see picture below: Disregarding the angle of the surface and any friction, calculate the velocity $v$ of a particle pulled back a ...
1answer
56 views

### Motion of Particle Described by Given Equation [closed]

I encountered a problem wherein I was given that the electric lines of force in a region varies as $$x^2+y^2=1$$ A charged particle was initially at rest at $(1,0)$. I had to answer whether the ...