# Questions tagged [forces]

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 the [particle-physics] tag for decay channels due to forces and [newtonian-mechanics] or one of the other subtopics of [classical-mechanics] for the dynamics of classical systems.

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48 views

### How does friction accelerate a car after rest?

If a car moves using the friction force from the rotation of the wheels, shouldn't a car be unable to accelerate immediately after the car is at motion, since there will be a friction force of equal ...
100 views

### Friction is also a conservative force?

$\color{red}{Warning \; ⚠️}$ :- This question is quite long and needs proper attention to the words used. I have asked a recent question about how spring force is conservative and in that I learnt ...
64 views

### Newton's 3rd law and Propellantless Propulsion

I was thinking lately about a potential misunderstanding regarding Newton's $3^\text{rd}$ law and the supposed impossibility of creating a device that moves by utilizing just internal forces (...
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### How do pulleys redirect force?

Consider this setup of three blocks, in which you would like to find the acceleration of the 8 kg one: One way I've heard to solve it is to consider the three blocks as one system and look at the ...
59 views

### Why is torque assumed to be constant?

Consider a spanner: I was doing calculations on how much torque would be applied on the bolt. To do this, I considered how much force was being applied at the full length of the handle. Then, I ...
31 views

### How can I relate torque with the tangential component of force times the radius?

In the book, Feynman lectures (Part 1, Section 18; 18–2: Rotation of a rigid body), the author says: $$∆W = (xF_y− yF_x)\Delta\theta$$ where $xF_y−yF_x$ is torque. He also says: Now let us consider a ...
40 views

### How much force does the wing beat of a large bird have?

For a large flying bird like the Andean condor, how much force in terms of lift and thrust does each wing beat have?
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### Field between parallel plates [closed]

What is this parallel plate configuration? Book says The field it sets up is uniform meaning that at every point the magnitude and direction is same inside the field. A vector E is used in figures in ...
18 views

### Solving spring mass damper system having non ideal viscous damper [closed]

How to solve a spring-mass damper system, where the damper is nonideal (i.e. has mass). And, what can be an equivalent system for the same. (i.e. using a mass and ideal damper in place of a nonideal ...
2k views

### Is spring force really a conservative force?

Let us consider this picture. $\Rightarrow$ The first picture shows the initial position of the block when the spring is in its natural length and is kept on a smooth horizontal table. $\Rightarrow$ ...
2k views

### How does Newton's third law hold up when a block kept on a table breaks the table?

Suppose there's a block of some mass that is kept on a table. But, instead of staying at rest on the table, it breaks through the table. How does Newton's third law hold up here? If the block is at ...
31 views

### Development of Propulsion system for standup paddle [closed]

I want to develop a propulsion system for a stand-up paddle even if it's already buyable. It should have the following specifications (extraction): max. speed: 7,2 km/h (2 m/s) Battery runtime: about ...
14 views

### Bodies falling at same rate [duplicate]

Why do bodies of different weight/ mass fall at same rate. Please do mention the mathematical explanation.
58 views

### General Newton's second law [closed]

Thank you, I apologize: next time i will use LaTeX. I ask to Vincent Thacker: I read your post but I ask if it is possible to get your last equation (or similar) in classical mechanics starting by d2/...
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### Max's Crash and Gs

I was watching the British GP recently. Max Verstappen, who was initially leading the race, crashed out. Thankfully, he is all well, but he suffered a 51G shunt. I have been wanting to know how these ...
37 views

### What does it mean when physicists say a force is carried by particle? [duplicate]

I read things like “photons carry the electromagnetic force”, and “the electromagnetic field is composed of photons”. How does this work? I know a little math ( master’s degree) and am not averse to ...
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### Is grain really a dipole?

Yesterday I was solving some electric field from resnik book and one of the solutions assumed a bee to be a sphere of charge $60 \;\text{pC}$ and the grain which sticks to it as a dipole due to ...
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### Forces on a closed container that can electromagnetically suspend objects

If you have a closed container (without air or other fluids, only with the object inside) that can electromagnetically suspend or maintain (not like if the container walls are covered with a single ...
30 views

### Tesla to Newtons Over Given Distance

I have a Neodymium magnet, for example, that has a magnetic flux density of $1.25 \;\text{T}$ and is 1 inch by 1 inch by 0.44 inches. I have a steel ball with a diameter of 0.5 inches placed 3 inches ...
45 views

### Does the conveyer belt in this question change anything? [closed]

With what minimum velocity should the block be projected from left end A towards end B such that it reaches to the other end B of the conveyor belt moving with constant velocity v. The friction ...
79 views

### Problems of Rotational Body at Uniform Speed [closed]

In this figure, $1.5 \;\text{kg}$ mass is connected to a $2 \;\text{kg}$ mass through a inflexible string. The $1.5 \;\text{kg}$ mass is on the surface of a table and through a hole on the table the ...
32 views

### What is the centripetal force acting on the bob of a simple pendulum?

One might say that the tension force $T$ is the centripetal force, but $T$ has been already cancelled out by $mg\cos\theta$. So, either the tension force has been balanced/cancelled by $mg\cos\theta$ ...
59 views

### How does down-wind faster than the wind (over-land) really work?

There has recently been posts on youtube where in a land based propeller/fan driven tricycle (blackbird) has been shown to roll faster than the wind that is behind it. The youtube channel veritasium ...
### Fluid buoyancy why is $F_{\text{buoy}}=W_{\text{air}}-W_{\text{w}}$? [closed]
I am having trouble understanding the reasoning for a solution for a buoyant forces question. The density of a human body can be calculated from its weight in air $W_{\text{air}}$, and its weight ...