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 ...
2
votes
3answers
566 views
Example in the book: A simple accelerometer
A simple accelerometer
You tape one end of a piece of string to the ceiling light of your car and hang a key with mass m to the other end (Figure 5.7). A protractor taped to the light allows you ...
1
vote
1answer
112 views
Calculating the acceleration of a car
I'm trying to calculate the maximum acceleration a car can achieve with the current gear ratio. I am ignoring drag forces and friction to keep it simple.
I'm doing this by:
calculating the torque ...
4
votes
2answers
117 views
Physics behind the flow of gas coming out of a balloon
I'm working with stratospheric balloons (latex ones) and I want to put a valve on it so it can float for a longer time. I'm trying to define which valve I should use, which demands I estimate the flow ...
2
votes
2answers
459 views
Ski Jumper's vertical velocity after 246.5m record?
What would be the vertical velocity of this ski jumper (ski flyer), after he first touches down, after he breaks the record with a 246.5m jump? What g force would he experience as he slows down?
...
-1
votes
1answer
37 views
Mass of a jumper, given height jumped and force exerted [closed]
This is the question:
An exceptional vertical jump from rest would raise a person 0.83m off
the ground. To do this, a constant force of 2593N would need to be
exerted against the ground. ...
0
votes
1answer
146 views
Force due to combination of free space and dielectric
I will make a generalized form of my question.
There are two point charges $q$, $x$ distance apart.
And there is a dielectric slab of thickness $t$ and of dielectric constant $K$.
Should the force ...
0
votes
0answers
20 views
Some basic questions about electric field & nucleus [duplicate]
I am not good in physics.You can say I am beginner in this field.
I have some basic questions.
I ju st want to know that
[1] If there is repulsive force between same charges proton-proton then why ...
-1
votes
0answers
27 views
Let F(x,y,z)=−c(r/||r||3) be the force resulting from the inverse square law… [closed]
c is a constant and r=(x,y,z). Show that f(x,y,z)=c/sqrt(x2+y2+z2) is a potential function for F. What can be concluded from any path from point A to point B in F? What can be concluded about a simple ...
2
votes
0answers
46 views
Robot controling pouring process from a bottle
I need to solve a problem within mechanic of fluids for a part of my thesis. Robot will pick up a bottle of beer, cola, julebrus or any other kind of beverage. And then it has to bring it to the glass ...
4
votes
5answers
4k views
Newton's second law of motion in terms of momentum
I am reading a document and in answer to the question State Newton’s second law of motion the candidate answers that The force acting on an object equals the rate of change of momentum of the object. ...
0
votes
1answer
158 views
Deceleration of Vehicle off pavement
How would I calculate the deceleration of a vehicle (ATV), wheels locked, on dirt? How long would it take to halt? How fast is it decelerating?
I used this calculator, but it seems incorrect for a ...
2
votes
1answer
62 views
Convert a 200mm linear stroke into 90 degrees motion
Can anyone help me Convert a 200 mm linear stroke into 90 degrees motion with as much mechanical advantage as possible or into two 90 degrees motions with as much mechanical advantage as possible?
...
0
votes
3answers
124 views
Why does a rod rotate?
I'm a physics tutor tutoring High School students. A question confused me a lot.
Question is:
Suppose a mass less rod length $l$ has a particle of mass $m$ attached at its end and the rod is ...
0
votes
1answer
111 views
Opposing forces on an air cylinder
If an air cylinder is pushing two platens apart with a force of 100lbs, do the platens need to push back at 100lbs or 50lbs each to keep the cylinder from moving? Assume no friction and both platens ...
7
votes
1answer
248 views
Is acceleration an average?
Background
I'm new to physics and math. I stopped studying both of them in high-school, and I wish I hadn't. I'm pursuing study in both topics for personal interest. Today, I'm learning about ...
0
votes
3answers
652 views
Who is right? Force exerted on a body. Me or my friend?
Three masses $m_1 = 3\text{ kg}$, $m_2 = 9\text{ kg}$ and $m_3 = 6\text{ kg}$ hang from three identical springs in a motionless elevator. The elevator is moving downward with a velocity of $v = ...
0
votes
2answers
46 views
Force applied in a body moving at high speed
Consider a rod of length $l$ and uniform density is moving at high speed. I want to deflect the rod where should I need to apply the minimum force, so that the rod is deflected..?
2
votes
2answers
86 views
Forces involved in strapping something down
Say I have a hollow cylinder and I wanted to strap it down to the bed of a truck. I would tension the strap on one end, and it would exert a force on the cylinder. My intuition tells me that the strap ...
15
votes
8answers
5k views
How exactly does curved space-time describe the force of gravity?
I understand that people explain (in layman's terms at least) that the presence of mass "warps" space-time geometry, and this causes gravity. I have also of course heard the analogy of a blanket or ...
4
votes
3answers
1k views
Which will stop first a heavier car or a lighter car?
If the friction from brakes, wind resistance and all such factors remain constat, which will stop first? A heavier car or a lighter car? How will the momentum of the car and graviational pull on a ...
0
votes
1answer
86 views
Problem solving moments in equilibrium
Two straight ladders, AC and BC, have equal weights $W$. They stand in equilibrium with their feet, A and B, on rough horizontal ground and their tops freely hinged at C. Angle CAB = 60$ ^o$, angle ...
1
vote
2answers
62 views
Resolution of vectors
What is the fundamental basis of resolution of vector. Suppose we have a vector $\vec{mg}$, now we resolve it into two components, horizontal and vertical. My question is what is the basis for telling ...
0
votes
1answer
31 views
Find the bending moment of a pole attached to a moving block
I'm having trouble with the following problem.
What I've done so far:
x-y is the usual coordinate system.
$a=\frac{F}{m}=\frac{800}{60}$ and the y component of this is $a_y=a\sin{60^\circ}$.
To ...
-1
votes
3answers
131 views
What needs to be integrated to solve this problem?
An object is placed on a frictionless table with its one end attached to a cord which is connected to a pulley and the tension is maintained constant at 25 N. what is the change in kinetic energy ...
5
votes
2answers
155 views
Relativistic equivalent of a spring-force?
Usually what helps me understand a concept better in physics is to write a simulation of it. I've got to the point where I'm competent in the basics of special relativity, but, I can't figure out how ...
0
votes
0answers
72 views
Tension $T$ in cable [closed]
Calculate the tension $T$ in each cable, as well as the magnitude and direction of the force exerted on the strut by the pivot in each case mostrados.En systems, w is the weight of the suspended box, ...
1
vote
2answers
989 views
Why does a ball bounce?
If an object is acted on by equal and opposite forces then it will be in equilibrium, and it's acceleration or velocity (and so direction as well) will not be changed.
So when a ball bounces, it ...
3
votes
3answers
135 views
Non-SHM oscillatory motion
How to solve these kind of questions , where $|F| \propto x^2$?
How to find time period and velocity type related things to the oscillatory motion?
...
0
votes
1answer
61 views
Find the dielectric constant of the medium?
Two point charges a distance $d$ apart in free space exert a force of $1.4\times10^{-4}N$. When the free space is replaced by a homogeneous dielectric medium, the force becomes $0.9\times10^{-4}N$. ...
13
votes
7answers
2k views
What does it mean to say “Gravity is the weakest of the forces”?
I can understand that on small scales (within an atom/molecule), the other forces are much stronger, but on larger scales, it seems that gravity is a far stronger force; e.g. planets are held to the ...
0
votes
0answers
42 views
Do all the 4 forces of nature act at the same speed? [duplicate]
It is believed that gravity, the weakest of the four forces propagates at the speed of light, cf. e.g. this Phys.SE post. One would expect (perhaps erroneously) that the other, stronger, forces acted ...
1
vote
1answer
71 views
Hydrostatic pressure at lateral directions
I just read that, with respect to a stationary tiny cube, suspended in a fluid, that has a negligible weight and dimensions:
Pressure is the same in every direction in a fluid at a given depth, ...
2
votes
1answer
58 views
How does the buoyant force on a cube at the bottom of a tank of water manifest itself?
Let's say a 10N cube (in air, on Earth) rests flat on a scale at the bottom of a tank of water, and the scale reads 8N, so there is 2N of buoyant force on the cube. How does the buoyant force ...
4
votes
2answers
126 views
Relativistic Lorentz force law
If we consider the the relativistic Lorentz force law:
$$\frac{d}{dt} (m\gamma \vec{u})=e(\vec{E}+\vec{u} \times \vec{B})$$
How can we deduce:
$$\frac{d}{dt} (m\gamma c^2)=e \vec{E} \cdot \vec{u}$$
...
0
votes
1answer
31 views
Work done by complex field on complex plane
A force field is given by $F = 3z+5$. Find the work done in moving an object in this force field along the parabola $z = t^2 + it$ from $z = 0$ to $z = 4+2i$.
I don't understand why conjugate ...
1
vote
3answers
123 views
Is the tension in both ends the same (on a massed string)?
If two blocks lay on a table and I pull the second block, as shown in the picture below. Is the tension in both ends of the string the same? (The string has a mass)
-1
votes
2answers
59 views
Changing Direction in a Vaccum [closed]
If a mass of one kilogram is traveling at one meter per second at 90 degrees, how much energy is required to get it to travel going 180 Degrees?
1
vote
1answer
127 views
Newton's Third Law of Motion
I want to start off by saying that I've looked around for other explanations, but I've not really found any satisfying ones. My question is basically the whole "Why can anything move at all?" ...
1
vote
2answers
93 views
Accelerating an elevator
A person is standing on a weighing scale in an elevator in upward acceleration.
Let $N$ be normal reaction force exerted by the weighing scale to the person (upward).
It is known that the person ...
4
votes
3answers
419 views
Infinite acceleration?
Why is acceleration regulated by mass? In a frictionless environment, why doesn't an object move at infinite acceleration if force is applied on it?
Force causes movement, so unless there is an ...
1
vote
1answer
103 views
rate of change of spring potential energy $\frac{dU}{dt}$
Suppose we have a setup like this. In orange are two wooden sticks sort of things, and they are attached to the block of mass $m$(as usual) at a joint which is hinge type something. A similar ...
2
votes
3answers
105 views
Is electron velocity at induction higher than in a wire?
When looking to the electrostatic induction on a microscopic level, do the electrons really move with high velocities or they move like when a current passes through the wire (slowly).
1
vote
2answers
48 views
effect of vertical collision on kinetic friction and subsequent change in horizontal velocity
Suppose somehow a block of mass $m$ is moving on ground, and the coefficient of kinetic friction between the block and the block is $\mu_k$. If I drop a tennis ball(of same mass) on it from a ...
2
votes
1answer
121 views
Is there a geometrical way to obtain a relationship between these vectors?
Suppose we have a setup like this. Here $a_1,a_2,b_1,b_2$ are acceleration magnitudes($b_1,b_2$ being relative) and $P,Q,R,S$ are not pulley/blocks but are points on the rope. If I use a geometrical ...
2
votes
4answers
104 views
Why in $F = iLB$, $L$ is a vector but $i$ is not?
I learned $F = iLB$ recently. However, I don't understand why $L$ is marked as a vector but $i$ is not.
For a normal rod, how should I define the direction of length vector $L$? And if I reverse the ...
3
votes
2answers
85 views
What causes acceleration of particles in the expansion section of a De Laval nozzle?
A De Laval nozzle has a compression section, where the propellant is compressed (and thereby accelerated) as it moves towards a narrow section (the throat). After the throat, the nozzle widens out ...
2
votes
2answers
109 views
Movement of man and ladder and their center of mass
Suppose there is a massless frictionless pulley.
A rope over it carries a mass $M$ and on other side carries a ladder of mass $(M-m)$ and a man on that ladder, of mass $m$. Now the man starts ...
1
vote
1answer
107 views
Work done by friction
Suppose we have a block of mass $M$ and we are moving it up a curve, very slowly ($a=0$). The surface is not smooth, and coefficient of friction is $\mu=\mu_s=\mu_k$.
To move the block we apply a ...
0
votes
0answers
42 views
Does distance increase force at impact? [closed]
If a car that weights 1800 KG is traveling at 2.235 ms would it with greater force and 25 feet than 10 feet?
My calculations say it would be the same if the road was level and the same surface ...
-1
votes
1answer
101 views
Vector Addition — Direction
Say we have three forces $F_1, F_2, F_3$, such that
$$
F_1 + F_2 - F_3 = 0\hspace 10mm (1)
$$
And let us say that $F_1$ and $F_2$ have the same direction and magnitude, and that $F_3$ has double the ...
