Tagged Questions

This tag is for the classical concept of forces, i.e. the quantities causing an acceleration of a body. It expands to the strong/electroweak force only insofar as they act comparable to ‘classical’ forces. Use [tag:particle-physics] for decay channels due to forces and [tag:newtonian-mechanics] or ...

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4
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3answers
230 views

Why is it mandatory to lose energy to an opposing force?

A body must do work against an opposing force to continue motion. I have found this statement many times. But what is the reason behind it? Suppose $F_1$ is acting on a body to accelerate it (to ...
1
vote
1answer
36 views

Is there an equilibrium for water and air in a tank?

I'll try my best to explain my question with examples because I don't have much knowledge on the theory. So say that I had a block of water in air, a cube of water, that is dropping. If the cube ...
2
votes
1answer
47 views

Just for confirmation: About conservative forces [closed]

Once I posted in the following thread and wondered, how I could picture/understand conservative forces best. I think, that I understood my problem now and everything became clearer. So just for ...
1
vote
2answers
57 views

Why is force a localized vector and not a free vector?

A vector which is drawn parallel to a given vector through a specified point unlike free vector in space is called a localised vector. The effect of a force acting on a body depends not only on the ...
4
votes
1answer
36 views

Physics behind the “Switch Pitch”?

I've come across this toy called a "Switch Pitch" designed by Chuck Hoberman. It's a ball that when tossed into the air (with some amount of rotation), inverts and changes colour. Made of plastic, ...
9
votes
1answer
1k views

Would you die before reaching the ground?

If you were to jump off a tall building, let's say Burj Khalifa, is it true that the pressure difference would be so strong as to kill you before reaching the ground?
0
votes
1answer
18 views

Foucault currents with a simple pendulum

I have this diagram : It's a kind of pendulum; when it swings, it passes through a small aera where there is a magnetic field. Therefore, the electrons moves towards the bottom because of a Lorentz ...
0
votes
1answer
26 views

Calculation of the g-force acting on people in a fake fun ride

I saw this video: https://www.facebook.com/video.php?v=622261007879030&set=vb.100002854081079&type=2&theater If you go to minute 1 and 2 seconds you see a fun ride in action. Obviously ...
1
vote
1answer
60 views

Moment of inertia from torque and angular acceleration measurements

I tried to calculate the moment of inertia of a quadcopter along its roll axis using two different methods and the results do not match. Method 1: measuring the period of a bifilar pendulum, I obtain ...
1
vote
1answer
30 views

Wheel dynamics: reaction forces with ground

I am confused by part of a dynamic model in this paper: http://waset.org/publications/4405/real-time-control-of-a-two-wheeled-inverted-pendulum-mobile-robot see page 3, figure 5. All forces labeled ...
-3
votes
1answer
55 views

If a 2,400 lb. car is moving at 1 mile per hour, how much force is required to stop its motion? [closed]

Given that I stand behind or in front of a car and someone will move the car from within at approximately 1 M.P.H., how much force is needed to stop the force driven by the engine to put the car at ...
0
votes
1answer
55 views

What is the net force acting on a climbing man by the rope?

I am confused with determining the net force on the climbing man below by the rope. My analysis is as follows. Let the tension be $T$. As both hands hold the rope then there are $T+T=2T$ upward acting ...
0
votes
1answer
22 views

Hydrogen bond and van der Waals bond

Just now I am studying about hydrogen bond and van der waals bond. I understand and able to differentiate between them but thinking of the similarities, do they have any?
2
votes
2answers
120 views

Weight versus gravitational force [duplicate]

What is the difference between weight and gravitational force? I am a beginner who want to study physics properly.
2
votes
0answers
62 views

Odd experiment results (electromagnetics)

Okay, a bit of background. So I'm working on a linear accelerator (you might know it as a Gauss rifle), and I had worked through the equations I thought I needed (Magnetic force, displacement, etc.) ...
1
vote
2answers
202 views

Why did I get this dynamics question wrong? [closed]

I'm wondering as to why I got this physics question wrong, despite it being quite simple in nature. I believe that I missed something while working on the problem. Basically, the question involves ...
2
votes
2answers
69 views

Nature of tension in a massless rope [duplicate]

I'm faced with a conceptual problem, where I am supposed to describe the motions of the following system (two masses on each end of a totally inelastic rope hanged on a pulley): I understand that ...
2
votes
1answer
81 views

Confusion with Newton's Second Law : Position & Time Dependence of Force

For a conservative force $\vec{F}(x,y)$ we have $$\vec{F}(x,y) = - \vec{\nabla}\phi(x,y)$$ where $\phi(x,y)$ is a potential function for $\vec{F}(x,y)$. Again, Newton's second law states that $$ ...
1
vote
1answer
42 views

How does the weight of the pendulum's bob cause a torque?

I know that a force will cause a torque if the force has a perpendicular component to the distance from the pivot point. However, in the figure above, I can't seem to visualize how the weight of ...
0
votes
1answer
39 views

Centripetal force in loop motion

I saw it from the book which talk about centripetal force in circular motion The main idea here is the balance in the term of relation between velocity and centripetal acceleration - centripetal ...
0
votes
1answer
69 views

Drag force on a flat plate

The solution for this apparently is $\frac{1}{2}C \rho A V^{2}$ where $C$ is the drag coefficient, $A$ is the area and $\rho$ and $V$ are the wind density and velocity. Let's do it without the drag ...
1
vote
1answer
53 views

Fictitious forces and $\omega$

I have been studying fictitious forces, such as the centrifugal force and Coriolis force. The equation for the centrifugal force is given by: $$F_{centrifugal}=-m\omega\times(\omega\times r)$$ My ...
0
votes
1answer
18 views

Various springs acting on a point mass

The force exerted on one spring is $\vec{F}=-k\vec{r}$. Now suppose we have N slinkys with stiffness $k_1,k_2,k_3,...,k_N$ where they have one end tied to fixed points in space with coordinates ...
4
votes
2answers
161 views

Newton's Third Law Exceptions?

Lately I've been brushing up on some of my old Physics texts from college. Most recently, I've been rereading parts of "Classical Dynamics of Particles and Systems (5th ed.)" by Thornton and Marion. ...
2
votes
3answers
172 views

Joules to do something

If my very limited understanding is correct, then, not accounting for gravity: 1 Newton can move 1 kilogram 1m But, can 2 Newtons move 1 kilogram 2 meters? Is this because 1 Newton = acceleration ...
1
vote
1answer
39 views

Joules To Move A Kilogram In Space [closed]

If roughly ten joules lifts one kg on earth one meter, how many in space? Meter / joule/kilogram Kilogram/meter/joule
1
vote
1answer
29 views

Does magnitude of a charge influence magnitude of force that individual charge exerts on another charge [closed]

two point charges, q1 and q2, are placed 0.3m apart on the x-axis, as shown in the figure above. Charge q1 has a value of -3 nano Coulomb and q2 has a value of +4.8 x10^-8 C. The net electric field ...
0
votes
1answer
35 views

What happens to the gas in the container in this picture when the container is tilted

So the test question asked what would happen to the gas if this container were tilted on its side. The piston shown here is 10 kg and moves frictionlessly. I said that the pressure inside the ...
1
vote
1answer
30 views

How to convert translational energy to rotational energy [closed]

Suppose that I have a body moving at certain velocity in straight line. So it has translational energy. I want to convert this energy to rotational energy of another body, by making the velocity of ...
-2
votes
2answers
39 views

Newtons laws velocity and acceleration [closed]

If a constant non-zero force is applied to an object, what can you say about the velocity and the acceleration of the object?
2
votes
2answers
44 views

Estimating the force needed to increase height of a mountain?

How would you estimate the force required by a tectonic plate to make the height of a mountain increase when it pushes against another? I've used a method to try and do it for Mt Everest and have ...
1
vote
3answers
94 views

Distinction between torque and force

Distinction between Torque and Force. Consider a case when a cylinder is rolling down a rough inclined plane. While analysing its motion, we consider the force applied by the friction and the ...
1
vote
1answer
36 views

Accelerated wedge [closed]

Consider the following figure, where a mass $m$ is placed on a wedge which is accelerated to the right ($\vec a$) which could be negative. The coefficient of friction between the mass and the wedge ...
1
vote
3answers
115 views

Direction of friction force between two boxes

There are two boxes on top of each other. The bottom box is dragged right by a constant force. What is the direction of friction of the top box against the bottom box?
4
votes
2answers
177 views

Is a chain REALLY only as strong as its weakest link

I heard this quote a lot (especially from my teachers) and I always wanted to know whether or not it was actually true. I think that its partially true; a chain with one weak link is weaker than a ...
1
vote
0answers
37 views

What is “W external” and “W internal” in Energy conservation law?

When I solve the energy conservation problem, I am confused when I have to make the term positive or negative. For example, someone throws a ball right up to the ground with velocity, $v$. The ball ...
0
votes
0answers
61 views

How strong is the force of space expansion?

There are many questions about space expansion, its cause, or its effects. But I have the feeling we never get straight and simple answers. I do not expect answers to be simple in general, but I ...
1
vote
2answers
44 views

The effect of windspeed on a car

I've worked problems in the past in trig class concerning the effect of wind on the speed of a plane and it's flight path and was wondering if a similar thing occurs with a car. First off, I'm ...
-1
votes
2answers
45 views

Does Centripetal Force Change Direction?

I have been struggling with this question that I have, "Does centripetal force change direction?" From every point, it points to the center. But if we draw its vector, we draw the tails from ...
1
vote
1answer
48 views

Modeling wall's behaviour

Sorry if the quesiton is inconvenient, but I judged the physics forum would be the best place to go. My house is divided in two parts by a wall, and there's some tree pushing it, so the wall is about ...
2
votes
6answers
345 views

Trouble understanding the concept of true and apparent weight

I need help understanding the concept of true weight vs apparent weight. I understand this much: if someone is standing in an elevator on a scale, the further up they go the less the reading on the ...
1
vote
0answers
21 views

Centripetal motion (Average force vs magnitude of velocity) [duplicate]

I had a homework question, regarding designing a centripetal motion lab, It asks me to determine the 2 constants if I'm performing a centripetal motion lab, trying to determine the effect that the ...
1
vote
0answers
27 views

Relationship between centripetal force and magnitude of velocity [closed]

In university physics we were assigned a Pre-lab on centripetal motion and asked to predict the effect that increasing the average force on the magnitude if velocity. Basically what I said is the ...
1
vote
2answers
62 views

What will happen in principle if one tries to push a neutron star?

When we push an object it moves due to the mutual repulsion between the electrons in our hand and the electrons in that object. Since a neutron star contains only neutrons, what will happen in ...
1
vote
2answers
46 views

Loads in decelerating a falling object

I'm new here and haven't looked at physics in any real depth since high school, 8 years. so apologies for any obvious mistakes. I remove trees in confined spaces setting up rigging systems, I am ...
2
votes
1answer
117 views

Finding the acceleration given only an angle

This is one of my homework problems for a College Physics I course: Dana has a sports medal suspended by a long ribbon from her rearview mirror. As she accelerates onto the highway, she notices ...
0
votes
1answer
63 views

The forces acting on 2 boxes [closed]

Consider the following figure: The surface is not friction-less. When the force $F$ is applied on mass A: Is the force the mass A applies on mass B larger, smaller or equal then the Force that B ...
3
votes
4answers
309 views

If a truck collides with a car, can the truck experience a larger force?

I am confused, here is a question: A large truck and a mini bus both have same velocity V and they collide and stop. The collision lasts for 1 second. A) Which one of the two will experience ...
0
votes
0answers
66 views

Why is area considered and not volume to find the force of a solenoid?

I am doing a project involving solenoids. I found multiple websites that say the force (in N) a solenoid exerts on a soft iron bar as it enters the coils can be given by the equation ...
3
votes
2answers
64 views

Wasted energy applying a torque

In another question I asked how find a way to desucee wasted energy, but I did not get a satisfactory answer. I have changed the setting here which brings us more close to the solution. Instead of a ...