-4
votes
1answer
54 views

Why do we believe in a “force” driven universe? [on hold]

Why do we not believe in the potential for a "unified force field" universe, to the exclusion of the belief in the potential for a mechanical, gear driven universe, if the correct shape for the gear ...
1
vote
1answer
38 views

Which inertial observer should I choose when using $\Delta U = -\Delta K$?

I just read and undertood that For any conservative force $F$ (which is not necessarily constant), we can define a potential energy change $\Delta U$ of an object on which the force exerts as ...
-1
votes
0answers
33 views

An inclined pulley system [on hold]

M1 and M2 both are 400g. There is no friction and the pulleys are massless. I am trying to work out the acceleration on M2. I am unsure whether the acceleration should be: $a\space =Mg\space -\space ...
0
votes
1answer
49 views

Which moves faster in a time $t$: $A$ or $B$? [on hold]

Suppose we have two objects, $A$ and $B$, both made of the same substance. They also have the same shape (e.g. two spheres), but $A$ is larger and therefore more massive than $B$. Both $A$ and $B$ ...
0
votes
1answer
28 views

Collision of a pendulum with other pendulums hanging at different heights

This is a question from a competitive test. I am not sure how to reason this out. By the length of the string, S should have the maximum amplitude. But this would be the case only when the pendulum ...
1
vote
2answers
56 views

Relation between the conservation of Energy and the conservation of Momentum?

I just learn about the momentum and it conservative attribute in a closed and isolate system and there is something I don't understand when I relate it to the conservation of the energy Considering ...
1
vote
1answer
32 views

Moment of inertia help [on hold]

Okay so lets say I have a lever with 2 objects on it, object one and object 2. Object 1 has a mass of $m_1$ and is $r_1$ away from the fulcrum; object 2 has a mass of $m_2$ and is $r_2$ away from the ...
13
votes
0answers
169 views

Underdetermined forces in a statics problem

I was trying to cook up a good exam problem on Newtonian mechanics, and I came up with one that I didn't fully understand myself. Always fun when you can outsmart yourself. In the figure a cylinder ...
0
votes
3answers
55 views

Reconciling Units in Classical System Analogies: Why Does Torque Have Units of Energy?

In classical physics we often cast an analogy between translational and rotational systems Force < > Torque Energy < > Rotational Energy Momentum < > Angular Momentum and considering SI ...
1
vote
0answers
23 views

Accelerating disk [on hold]

A disk of radius $R$ is accelerating to the right over a plane. At $t=0$ the speed and the acceleration of the axle are $v_1$ and $a_1$ what is the velocity and the acceleration of each point (1-4 ...
-3
votes
0answers
29 views

How to calcuate uniform circular motion? [on hold]

Given: Ideally, I maintain a speed of 265km/hr and 285 km/hr. Roughly, 73.6 m/s and 79m/s. I make a turn and experience around 4.5g's to 5.5g's, roughly 45 and 55 m/s^2, for about 7 seconds. I ...
0
votes
1answer
35 views

Catapult projectile with different mass [on hold]

We have a physics law. We made catapult and we have to launch a water balloon. However before that we have to know where the water balloon will fall. We don't have radars or stuff like that to ...
0
votes
0answers
49 views

How to describe the motion of a box initially at rest on a table rotating with an increasing angular speed? [on hold]

Consider the following diagram. A box is on a table that can move circularly and the box is connected by a string attached to the fixed bearing. At $t=0$, the box is at rest, the string of length ...
4
votes
2answers
454 views

Can a box on a frictionless rotating table rotate?

I am trying to digest the following problem. Suppose a block of mass $m$ lying on a horizontal, frictionless turntable is connected to a string attached to the center of the turntable, as ...
0
votes
0answers
11 views

Teeter Todder force of uplift [on hold]

What is the force of a 200lb man jumping from a three foot high elevation onto a four foot long teeter-todder with a four inch pivot point with a one hundred and thirty pound ma on the opposite ...
2
votes
3answers
618 views

While finding escape velocity, does human mass counts as the mass of Earth?

Escape velocity depends upon the mass of earth. my doubt is whether human mass adds into it or not? If it add then Earth's escape velocity would be increasing!
-1
votes
0answers
13 views

Motion in a straight Line [on hold]

A stone is projected from a height of 300m and at same time another stone is projected vertically upwards with a velocity of 100m/s Find when and where the two stones meet
0
votes
2answers
31 views

A bullet is fired horizontally from the top of a building, and at the same instant a second bullet [on hold]

A bullet is fired horizontally from the top of a building, and at the same instant a second bullet is dropped from the same height. Ignore air resistance. Which bullet hits the ground first?
3
votes
0answers
48 views

How do I treat the Lagrangian in the case of a rigid body?

Here's Exercise 1.11 from Goldstein's Classical Mechanics 3rd edition (the first one after having derived the Lagrangian basically): Exercise 1.11: Consider a uniform thin disk that rolls without ...
-1
votes
0answers
17 views

Newton's 3rd Law and Equilibrium [duplicate]

What is the difference between Newton Third Law and equilibrium?
1
vote
2answers
60 views

Newtons Third Law [duplicate]

In Newtons Third Law, it states that for every action, there is an equal but opposite reaction. So that means tat for every action, there will be a reaction to cancel it out. So if that is the case ...
2
votes
3answers
105 views
+50

Why do the agents of conservative force return work done against them to the body that worked on them?

Let a body moves & a conservative force opposes its motion by applying an opposing force on it. Therefore, by Newton's third law of motion, the body will also exert reactive force on the agent of ...
2
votes
4answers
88 views

Collision paradox

Suppose an insect travelling south at some velocity, collides with a train travelling north at some other (opposite) velocity. The insect hits the front of the train, where it splats to an ...
2
votes
4answers
118 views

Kinetic energy vs. momentum?

As simple as this question might seem, I failed to intuitively answer it. Let's assume there is a $10,000$ $kg$ truck moving at $1$ $m/s$, so its momentum and KE are: $p=10,000$ $kg.m/s$ and ...
0
votes
1answer
65 views

Landau Mechanics equation 16.9

I am having trouble deriving the equation 16.9 from Landau's Classical Mechanics book. This equation is the maximum kinetic energy of a particle if a massive particle with mass $M$ disintegrates into ...
-1
votes
0answers
14 views

Angular velocity and linear velocity [on hold]

Define and EXPLAIN average angular velocity and acceleration. Define and EXPLAIN instantaneous angular velocity. Experiment was about throwing a cricket ball. the shoulder is the point of reference. ...
1
vote
2answers
87 views

What causes damage, kinetic energy or momentum?

Let's assume we have 2 bullets. The first bullet has $450$ $J$ of KE and $3$ $kg.m/s$ of momentum, while the second bullet has $250$ $J$ of KE and $5$ $kg.m/s$. Now if they are both shot at ballistic ...
1
vote
2answers
42 views

Line integral calculates work, even though the force from the vector field doesn't cause the movement?

I'm afraid the title here was unclear, so I'll attempt to make things a bit more clear. I am conceptually confused about the physical meaning of line integrals over a vector field, so I'll pick an ...
1
vote
5answers
120 views

A force is exerted on a body, kinetic energy increases but no work is done by the force. Why?

After reading the article, I was totally perplexed . I was reading the External forces and internal energy transfers in Principles of Physics by Resnick,Halliday,Walker. It goes like that An ...
0
votes
1answer
18 views

Find force of friction on an object under influence of tension by another object

I conducted an experiment using video analyses software, and found the accleration of a box on a table being pulled by a string attached to a pulley on the edge of the table attached to the weight ...
0
votes
1answer
19 views

With what speed must e.g. a car drive into a turn so it won't drift out? [on hold]

I am trying to figure out the following question: with what speed must e.g. a car drive into a turn so it won't drift out (if a turn is a circumference of a semicircle)? e.g. $r= 5 m$ $a_r= ...
0
votes
1answer
52 views

How would the solar system change if the Earth were removed

I was reading a closed question with the same title and wondered if it would be on-topic with the following change: Could a large-mass object from interstellar space pass through the inner ...
0
votes
1answer
20 views

Newton's Third Law Opposite Angles

I am asking a related question here : Newton's Third Law Angular Bouncing Why, given newton's third law would a ball bounce at an opposite angle to it's original, if an equal and opposite force ...
0
votes
1answer
20 views

Newton's Third Law Angular Bouncing [duplicate]

I am asking a related question here: Newton's Third Law Opposite Angles If a ball is accelerating at a surface at a non-straight angle, it will bounce off with the opposite trajectory, like if ...
0
votes
0answers
15 views

Falling with air resistance speed as a function of distance [on hold]

Starting at 0 velocity and falling with air resistance $-mkv$, find the relation between speed and the vertical distance that an object falls. I went through the problem to find the equation of motion ...
0
votes
0answers
13 views

Acceleration of the rope holding two objects(one heavier than other) with both objects on different inclines [on hold]

How do you find the acceleration of the rope and what would this process look like condensed into one big formula?
0
votes
1answer
34 views

Projectile motion with air resistance limit question [on hold]

I have the equation for the max height $h$ of a projectile launched directly upwards with speed $v_0$ and air resistance force $-mkv$. I am trying to calculate the limit as $h$ goes to ...
2
votes
3answers
146 views

What is the significance of clamping the center of the spring?

7. A block is hung on a spring, and the frequency $f$ of the oscillation of the system is measured. The block, a second identical block, and the spring are carried in the Space Shuttle to space. ...
0
votes
6answers
207 views

Why is kinetic energy stored as potential energy in a body during its motion against gravity?

Everyone knows kinetic energy is converted to potential energy in the body when it moves up against the earth's opposing gravitational force. But I am facing some problem with this. What I learnt ...
0
votes
0answers
19 views

Best book for studying Newton's laws, conservation of momentum, etc [duplicate]

Best book for studying Newton's laws, conservation of momentum, etc, so that I can apply these laws anywhere. (I want to analyze fluids on my own.) I have studied bernoulli and Euler etc those ...
1
vote
1answer
90 views

Case of the mysterious bullets (taken from Mad About Physics)

"Two ideal bullets, identical in shape, size and mass, strike the same target with the same speed just before the collision. Force meters at the target register two times the force value for bullet A ...
1
vote
2answers
37 views

Effect of movements of astronauts on International Space Station

I know that astronauts move in and around in ISS. When they move they also touch the modules of ISS and sometimes they apply force on the module to move. When this happens, as far as I know it affects ...
-2
votes
1answer
24 views

Accelerating Tetrahedron [closed]

Four identical spheres are in contact with each other and form a tetrahedron. If acceleration of the top sphere is $a$, find the acceleration of the spheres on ground.
0
votes
1answer
56 views

Center of mass after explosion [closed]

How he treated the center of mass as if it is still in the same place , is not it supposed to change after explosion ? and is not explosion destroying the closed system? i mean it represents and ...
0
votes
2answers
73 views

Space Elevator: how would you keep the end of a Space Elevator's cable rigid?

I had a discussion with my wife about physics behind a Space Elevator. Imagine a cable rising 60k into the firmament for its elevator to climb. The cable would have to rotate in unison with the earth, ...
2
votes
1answer
90 views

Rolling a ball into a cone; what should the forces overall be?

This is my solution to finding angular displacement/velocity/acceleration on cone so far. Consider a cone, with an apex of half-angle $\psi$ pointing down, and a height of $h$. If I roll a ball into ...
2
votes
1answer
92 views

How did Newton establish his famous third law of motion?

For every action,there is equal and opposite reaction . This is the famous Newton's third law of motion. But how did he come to this conclusion? We can prove 2nd law using calculus. But how did Newton ...
3
votes
1answer
52 views

Non-deterministic particle system

This question is in the spirit of Norton's dome, an example of an apparently non-deterministic system in Newtonian mechanics. Under certain restrictions, the Picard–Lindelöf theorem guarantees the ...
0
votes
0answers
32 views

Plank stopping time (Continuation and Physical meaning)

A while back I asked this problem: "Plank stopping time" I thought it was solved, but now I have some questions about the solution. Problem: A plank of length $L$ and mass $m$ lies on a ...
1
vote
1answer
52 views

Simple Harmonic Motion homework [closed]

Suppose we have a rod of mass $m$ and length $l$ which is pivoted at center and two springs of spring constant $k$ are attached at opposite ends so that it performs simple Harmonic motion when ...