The rate of change of velocity of a body per unit of time.
42
votes
9answers
7k views
Don't heavier objects actually fall faster because they exert their own gravity?
The common understanding is that, setting air resistance aside, all objects dropped to Earth fall at the same rate. This is often demonstrated through the thought experiment of cutting a large object ...
3
votes
5answers
569 views
Confused about the role of mass
I'm far from being a physics expert and figured this would be a good place to ask a beginner question that has been confusing me for some time.
According to Galileo, two bodies of different masses, ...
9
votes
1answer
601 views
How do I calculate the (apparent) gravitational pull with General Relativity?
Assume a static metric with (known) components $g_{\mu\nu}$. I'd like to know what is the gravitational pull $g$ of a test particle placed on an arbitrary point $X$.
The gravitational pull being ...
9
votes
1answer
644 views
What came first, Rice Crispy or “Snap,” “Crackle,” and “Pop”? [closed]
The fourth, fifth, and sixth derivatives of position are called "Snap" "Crackle" and "Pop". What came first, the rice crispy characters, or the physics units?
7
votes
4answers
2k views
Acceleration in special relativity
I am currently studying the motion of relativistic charged particles in electromagnetic fields. More exactly, we first derived the equation of motion in the 4-vector formalism.
I was a bit confused ...
1
vote
6answers
1k views
Does light have acceleration?
Light travels with the largest speed in our universe. Does light have acceleration?
1
vote
4answers
4k views
Free falling of object with no air resistance
Why does an object with smaller mass hits the ground at same time compared to object with greater mass? I understand the acceleration due to gravity of earth will be same but won't the object with ...
4
votes
4answers
709 views
Is acceleration an absolute quantity?
I would like to know if acceleration is an absolute quantity, and if so why?
3
votes
2answers
492 views
Classical car collision
I have a very confusing discussion with a friend of mine.
2 cars ($car_a$ and $car_b$) of the same mass $m$ are on a collision course. Both cars travel at $50_\frac{km}{h}$ towards each other.
They ...
2
votes
1answer
421 views
Force on rope with accelerating mass on pulley
I have a pretty basic pulley problem where I lack the right start.
A child sits on a seat which is held by a rope going to a cable roll (attached to a tree) and back into the kid's hands.
When it ...
10
votes
7answers
2k views
Would it help if you jump inside a free falling elevator?
Imagine you're trapped inside a free falling elevator. Would you decrease your impact impulse by jumping during the fall? When?
1
vote
1answer
140 views
Accelerating elevator?
If your in an elevator accelerating downwards faster than gravity, would you be pushed up to the ceiling? Since gravity cannot match the acceleration of the elevator, you're wouldn't be able to move ...
6
votes
4answers
133 views
Integrating radial free fall in Newtonian gravity
I thought this would be a simple question, but I'm having trouble figuring it out. Not a homework assignment btw. I am a physics student and am just genuinely interested in physics problems involving ...
3
votes
2answers
961 views
Formulas for ball rolling in a bowl?
I'm developing a program where I've a ball/sphere rolling in a bowl from the side at top, till the center at bottom, and I'm trying to get the formulas for:
The rotation angle and the position of ...
2
votes
3answers
785 views
What is the velocity area method for estimating the flow of water?
Can anyone explain to me what the Velocity Area method for measuring river or water flow is?
My guess is that the product of the cross sectional area and the velocity of water flowing in a pipe is ...
2
votes
5answers
437 views
Why doesn't an electron accelerate in a circuit?
Why don't electrons accelerate when a voltage is applied between two points in in a circuit? All the textbooks I've referred conveyed the meaning that when an electron traveled from negative potential ...
5
votes
2answers
285 views
relativistic acceleration equation
A Starship is going to accelerate from 0 to some final four-velocity, but it cannot accelerate faster than $g_M$, otherwise it will crush the astronauts.
what is the appropiate equation to constraint ...
4
votes
5answers
4k views
Distance when acceleration not constant
I have a background in calculus but don't really know anything about physics. Forgive me if this is a really basic question.
The equation for distance of an accelerating object with constant ...
3
votes
5answers
398 views
If a space ship accelerated constantly, would its astronauts constantly feel the forward movement?
I know that if a space ship suddenly traveled very fast, its astronauts would be fly against the back wall, potentially getting hurt. If the space ship suddenly stopped, they would also fly against ...
3
votes
3answers
3k views
Ion Drive Propulsion Top Speed
I would like to know if there is some formula / graph which would provide / show the efficiency of a certain type of propeller in space. Specifically, I'm interested in the acceleration attainable at ...
1
vote
2answers
216 views
Using acceleration to plot position
Sorry if this question is dumb, and I know is physics 101, but I'm not that good with physics.
I'm writing an iPhone program that by collecting the acceleration data of the device tries to replicate ...
5
votes
1answer
119 views
Slinky base does not immediately fall due to gravity
Why does the base of this slinky not fall immediately to gravity. My guess is tension in the springs is a force > mass*gravity but even then it is dumbfounding.
3
votes
1answer
607 views
Is acceleration due to gravity constant?
I was taught in school that acceleration due to gravity is constant. But recently, when I checked Physics textbook, I noted that
$$F = \dfrac{G \cdot m_1 \cdot m_2}{r^2} $$
So, as the body falls ...
3
votes
2answers
506 views
Does a moving escalator make it easier to walk up the steps?
I was discussing with my colleagues why it feels easier to walk up an escalator when it is moving. My natural assumption was that the movement of the escalator imparts some extra acceleration on the ...
2
votes
1answer
135 views
How to find speed when accelerating down a slanted wire
I saw this picture on one of my social media sites with the caption, "I'd do this in a heart beat! Who's with me!"
I was about to go balls to the walls and say, "I'm in! When and where??" But then ...
2
votes
3answers
2k views
Convert acceleration as a function of position to acceleration as a function of time?
Suppose I have acceleration defined as a function of position, "a(x)". How to convert it into a function of time "a(t)"? Please give an example for the case a(x)= x/s²
1
vote
2answers
56 views
Clarification regarding Newton's Third Law of Motion and why movement is possible [duplicate]
Newton's third law states that to every action, there is an equal and opposite reaction.
If that's the case, then how do things move at all? Shouldn't all applied forces be canceled by the equal and ...
0
votes
2answers
1k views
What is the force exerted on a body that doesn't move?
If I push against a brick wall I'm exerting a force against the brick wall the the brick wall will exert the same force against me. These will cancel each other out and neither myself or the wall will ...
0
votes
2answers
2k views
Does an Increase of Force affect the Speed of an object if the acceleration stays constant?
If I had a mass of $100\:\rm{kg}$ accelerating due to gravity, using $F=ma$:
$F = 100\:\rm{kg} \times 9.8\:\rm{m/s^2}$
$F = 980 \:\rm N$...
If I increased the mass to 200kg, the force would be 1960 ...
-3
votes
1answer
240 views
Is antigravity the source of accelerating expansion (dark energy)?
Is antigravity the source of accelerating expansion(dark energy)?
From the observation of 1998, we found that our universe has been continuing accelerating expansion, and the unknown cause for this ...
