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.

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2
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2answers
22 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 ...
0
votes
2answers
18 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 ...
2
votes
3answers
58 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 ...
0
votes
1answer
23 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 ...
0
votes
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 ...
6
votes
1answer
71 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 ...
0
votes
1answer
48 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?
0
votes
4answers
65 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 ...
1
vote
2answers
39 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 ...
1
vote
0answers
16 views

Suspended mass in motion free-body diagram [on hold]

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 ...
0
votes
1answer
28 views

When you are standing in a running train if you jump means will you be in same place or will you be in front or back? [duplicate]

When you are standing in a running train if you jump means will you be in same place or will you be in front or back?
1
vote
1answer
9 views

What is difference between anisotropy and inhomogeinity of this type of composite material?

I am studying some types of composite materials having 2 phases - fibers and matrix. I have some questions and confusions. Any help is appreciated. The composite has fiber along length and I am ...
0
votes
1answer
44 views

Block on an inclined plane, spring at bottom of incline [on hold]

Problem: A block of mass $m = 5.00kg$ is on an inclined plane with an angle $\theta$ = 16.26 degrees with respect to the horizontal. The coefficients of static and kinetic friction are: $\mu_{k}$ = ...
0
votes
1answer
50 views

Spring on a cart problem [on hold]

The problem is two dimensional. At t = 0, a stationary cart at initial position (0,0) starts to accelerate with acceleration a in the negative "x-axis" direction. On the cart, there is an isosceles ...
-2
votes
0answers
78 views

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

The black arm is turning clockwise at $w1$. The blue axis is fixed to the ground. The grey cruz (grey arms) is turning at $w2$, with $w2 < w1$, so the grey cruz is turning around itself ...
27
votes
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 ...
0
votes
0answers
35 views

Theory books for physics upto Irodov level [duplicate]

Problems in Physics by IE Irodov is a very popular book amongst students for problem solving. It has very good problems. However, most of the popular high-school physics textbooks like Resnick ...
0
votes
0answers
19 views

Is there an applied force acting on the balloon? [duplicate]

A long string is running through a straw with a blown-up balloon taped onto the straw, and a penny taped onto the balloon. There should be a support force going up, gravity going down, friction force ...
0
votes
0answers
23 views

How are Newton's Laws of motion related to the amount of work exhibited by the balloon vehicle? [on hold]

A long string is running through a straw with a balloon taped onto the straw, and a penny taped onto the balloon.
1
vote
0answers
35 views

Mach's principle in empty universe, centripetal force and violation of Newton's laws of motion [on hold]

Questions about Mach's principle and empty universe has been asked many times but nowhere can I find it's cross examination with centripetal force. From my point of view the simple logic of ...
1
vote
1answer
56 views

What is the point of this type of graph? (Projectile) [on hold]

What is the point of graphing vs range, during kinematic motion?
0
votes
1answer
31 views

Will the particle reach other end?

I place a container at rest in vaccum and filled it with air (STP conditions). Suppose a moving particle(sphere of dia 2mm) is placed at one end of the container without disturbing anything, will ...
1
vote
2answers
58 views

Will a person experience micro or zero gravity inside an aeroplane in free fall

Let us say that a person is inside a stationary aeroplane being held by a stationary helicopter in the sky. Now, the cable which supports the aeroplane breaks. Thus the aeroplane is now not bound by ...
0
votes
1answer
26 views

How to find amplitude?

What are the general methods of finding amplitude in various cases of simple harmonic motion containing spring block system? I always try with the basic sine formula of SHM to find amplitude.
3
votes
3answers
78 views

Variable mass dynamics: Particle and Rigid Body

I'm encountering some issues in the understanding of some basic concepts about the dynamics of variable-mass particles and rigid bodies. For what I found, for example reading On the use and abuse of ...
0
votes
0answers
15 views

What is the minimum velocity an object needs to hit a vertical hanging rod with, so it it can make a revolution? [on hold]

The Rod is handing vertically, Attached to a firm end. An object of mass m hits it with velocity v, so what minimum value does v should have so this rod can rotate about its pivot?
-1
votes
1answer
29 views

What is the radius of the circular orbit? [on hold]

Find the radius of the circular orbit of a satellite moving with an angular speed equal to the angular speed of Earth's rotation. I started with the relation of time period ad the radius.
0
votes
1answer
34 views

Conservation of momentum 1-D problem: track is not level

This problem is a standard kind of 1-D problem. You have 2 equal carts approaching each other and collide on linear air track. BUT the person setting up the track did NOT do a good job at making the ...
0
votes
0answers
28 views

What is the true weight in the geostationary satellite? [on hold]

What is the true weight of an object in a geostationary satellite that weighed exactly 10.0N at the north pole? I did: At north pole the weight of the body is 10 N. Therefore the mass of the body is ...
0
votes
0answers
31 views

kronecker product of representations on SU(2) group [on hold]

We know that if we have two irreducible representations, their product is in general reducible : $$T^{\mu}\otimes T^{\nu}(g)=\oplus \sum_{\lambda}c_{\lambda}T^{\lambda} (g)$$ where $c_{\lambda}$ is ...
2
votes
1answer
64 views

Can we measure kenetic energy on an absolute scale, or does it have to be measured with reference to something else?

I recently read the question Kinetic energy of an object at rest where it was suggested that the kinetic energy of an object on Earth is measured in the reference frame of Earth. Can we measure ...
0
votes
1answer
26 views

Will a heavier or lighter tank shell / bullet/ etc. travel further given the same starting energy?

Let's say I have for example two tank shells, both being the same size and having the same shape. Let's say the starting energy is 100kg*m/s^2, and the one shell is 1kg, the other 25kg. 1kg * ...
0
votes
2answers
22 views

Damping Constant for a Ball Rolling in a Bowl

How would you find the damping constant of a ball rolling without slipping in half of a sphere? I know how to find the period of the oscillation, but how would I find the damping constant ...
-2
votes
0answers
9 views

Parabolic motion exercise [on hold]

From the top of a building, when t=0, a ball is thrown with a speed of 50m/s, forming a 30° angle over the horizontal. The ball hits the street, wuth a 40° angle below the horizontal. Find: a) Time in ...
0
votes
4answers
48 views

Car driving / falling off of a cliff - will it land upright?

In a recent episode of The Walking Dead, a van was pushed off of a bridge and flipped once and landed upright, on all four wheels. Assumption: the ground and cliff are both flat. Will a vehicle ...
6
votes
2answers
1k views

Kinetic energy of an object at rest

Why don't we consider that an object on Earth has kinetic energy as it is also moving at the rotating speed of Earth?
0
votes
0answers
20 views

Relative acceleration: frame of references

There is a question I've been struggling with, and I ask for your help to understand it fully. Q: An inclined plane, fixed to the inside of an elevvator, makes a 32 degrees angle with the floor. A ...
0
votes
1answer
16 views

Maximum velocity on Unbanked roads and why should friction be more than centripetal force? [on hold]

Why is maximum velocity on unbanked circular road given by $\sqrt{urg}$ where $u$ is coefficient of friction, $r$ is radius of circular track and $g$ is acceleration due to gravity? Why should ...
2
votes
1answer
42 views

Coupled ODEs that model a quad rotor

I am working on modeling the vibrations of a quad rotor. The arms that support the rotors are fixed to a center plate; that is, it is pretty much a cantilever beam with an end load. Since this is the ...
0
votes
0answers
28 views

Centrifugal force on a space station - how many RPM? [on hold]

What is the RPM needed to have 1G simulated gravity on a cylindrical space station that is 1000 meters in diameter? What is the equation to calculate that? [edit] I know that in this case it's the ...
0
votes
0answers
29 views

Angle of throwing a ball in a train moving in an arc [on hold]

Suppose a man is standing in the middle of a train car, when the train is riding with speed $V_T$ on a track section with circular curvature of radius $R$. The man wants to throw a ball with velocity ...
0
votes
1answer
28 views

Liquid placed in a rotating cylinder

The Question A closed vertical cylinder is filled with an incompressible liquid of mass m completely. The cylinder is now sealed from all sides and rotated about ...
0
votes
0answers
29 views

Calculating the moment of inertia in bifilar pendulums

I'm an A2 student, and I've been looking into how experimental and theoretical determined mass moments of inertia differ. I came across a method (search Youtube for Measuring Mass Moment of Inertia - ...
0
votes
0answers
8 views

How does live load versus dead load effect roof slip-resistance testing?

I have tested a wide variety of roofing materials for slip resistance in a range of roof slopes using various boot outsole materials. With all test protocols, equipment, and conditions being equal, ...
2
votes
0answers
18 views

Question about massive spring and SHM [on hold]

A mass $M$ is resting on the end of a spring with constant $K$. The mass of the spring is $m$, and the displacement of each element of the spring is proportional to the distance from the fixed end ...
0
votes
0answers
15 views

Sliding Atwood? Moving Stoplight? [on hold]

This version of an Atwood machine has two posts, separated by a known distance, with pulleys at the top. Running over the pulleys is a string of known length with three different masses: one on an ...
2
votes
2answers
117 views

What motion can emerge in a still universe? [duplicate]

I consider a very large non homogeneous cloud of dust in isolation. No external gravitational interactions. It is initially completely still and start collapsing under the its own gravity. Can the ...
4
votes
2answers
54 views

Friction Between Liquid and Solid Surface

How does friction between liquid surface and solid surface differ from viscosity, the friction between liquid and liquid surfaces? Also has a word describing the process been invented or is ...
2
votes
2answers
96 views

Velocity of car down an Inclined Plane

I was learning to make a car game and came across this situation where my car is on an inclined plane. It's initial velocity is 0. Now, the problem is that my memory serves me this formula to ...
0
votes
1answer
25 views

Where is the direction of kinetic friction in this question?

Suppose there is on object of 20.0kg sliding to the right. A person exert a force of 30N left on the object. The object has an acceleration of 2.5m/s^2 left. What is the magnitude and direction of ...