The rate of change of velocity of a body per unit of time.

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25
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10answers
4k views

Why is acceleration expressed as m/s/s?

I'm a philosophy student (I, regrettably, don't know calculus or much physics). Last year I spent some time learning how work, power, speed, velocity, energy, force, and acceleration relate. But I was ...
-1
votes
1answer
53 views

What is the frictional force of this car? [closed]

The breaking acceleration for a car is $-12.2\frac{m}{s^2}$. The car has a mass of 925kg. I want to find the frictional force. Here is what I have so far: $$\Sigma\vec{F} = m\vec{a}$$ $$\Sigma\vec{F} ...
1
vote
2answers
47 views

Position with respect to time with friction

I'm interested in equations of motion when friction is present for a little graphical side project I am working on. I'm really rusty with physics, so I apologize if this is a basic question or doesn't ...
0
votes
1answer
59 views

Accelerometer on a wheel's rim [closed]

If I put a 3-axis accelerometer on a vertical wheel's rim which acceleration is going to give to me? Will the gravity interfere my results?
0
votes
1answer
108 views

If an electron can't go faster than light, how is energy conserved here?

I came across a physics question recently about accelerating electrons with potential differences and it got me wondering. Here is the question that brought the concept to mind. First off, imagine ...
0
votes
2answers
92 views

velocity required when rounding a flat curve and banked track

When rounding a flat curve, the centripetal force is provided by the frictional force. I learned that when a car rounds a flat curve with a fixed radius $R$, it can be able to make a turn as long it ...
0
votes
1answer
68 views

Acceleration reaches speed of light? [duplicate]

Hi, I am thinking about acceleration. Let's think we have a force of $1$ N and a particle of $1$ kg, then acceleration will be $1$. So the speed gets higher every second and $c$ seconds later, in ...
0
votes
1answer
234 views

Accelerated liquid in a U-tube

Consider a U-tube containing some liquid. The two ends of the tube are connected to closed volumes of air with different initial pressures, such that there is some difference in the liquid levels ...
0
votes
0answers
155 views

Gravity change as a function of time only

Is it possible to find how gravity changes with time? That is, height is not part of the equation. For example, $g$ can be expressed as a function of height that does not involve time with this ...
0
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2answers
109 views

Exact definition of momentarily comoving reference frame (MCRF)

Consider a particle $P$ in the framework of special relativity with position $r(t)=(ct,x(t),y(t),z(t))$ respect to an inertial reference frame $\Sigma=(ct,x,y,z;O)$. I need to know if the following ...
0
votes
1answer
79 views

What is empirical mean of centripetal acceleration

We have this formula for centripetal acceleration - $a = v \frac{d\theta}{dt} = v\omega = \frac{v^2}{r}$ but in case of usual acceleration i know that speed in $t_1 = v_0 + a \cdot (t_1 - t_0)$ but ...
0
votes
2answers
146 views

Why would an electron in an orbit be accelerating continuously and would thus radiate away its energy and fall into the nucleus in a classical model? [duplicate]

I was reading this answer by madame anna v: You are right, the planetary model of the atom does not make sense when one considers the electromagnetic forces involved. The electron in an orbit is ...
0
votes
3answers
101 views

Velocity vector for constant acceleration in newtonian mechanics

If the acceleration vector of an object remains constant, is there no change in the direction of the velocity vector? The question applies to any movements in classical physics.
0
votes
1answer
91 views

What is this vector problem asking to find, the magnitude of the force F or the component of it that goes along the ramp?

A shopper pushes a 7.5-kg shopping cart up a 13 (degree)incline. Find the magnitude of the horizontal force, F, needed to give the cart an acceleration of 1.41 m/s$^2$. I ask this because the ...
5
votes
2answers
202 views

Does velocity or acceleration cause time dilation?

What causes time dilation? Acceleration or velocity? I've seen multiple comments on this forum that assert velocity is the cause, but that doesn't seem right to me. You can't have velocity without ...
3
votes
2answers
103 views

Velocity and acceleration in SHM

Can velocity and acceleration reach maximal values during the SHM simultaneously? Can you explain why?
2
votes
0answers
99 views

How do we derive force/acceleration vectors from Einstein's field equations?

I'm new here and I don't have any formal experience in physics beyond A-level. I've been exploring an idea for a space sim game someone else is developing in which propulsion of a spacecraft is ...
0
votes
2answers
86 views

How to find time, acceleration under this situation

I am trying to solve the following. An object of mass $m$ slides on a horizontal surface with initial velocity $v_0$. If the kinetic friction between the object and mass is given by $\mu$, find ...
1
vote
1answer
68 views

Acceleration and Newton's third law

I am puzzled with the following problem. A man starts to jump. First he will exert force on the floor and he starts accelerating upwards. Then he is off the floor. What is the relationship between ...
0
votes
3answers
104 views

Net force and its concept

I am trying to understand net force intuitively and this is what I think. If a net force is towards the positive $x$ direction, which of the following is true ? a) It can be moving in the ...
13
votes
1answer
284 views

Do accelerated charges radiate or not?

This questions has been asked all over the net (here included) but I can't find a satisfactory answer or discussion. Some say it does not radiate if the acceleration is caused by a uniform gravity ...
1
vote
4answers
187 views

Acceleration of a car in a collision?

For example because of newton law $F=ma$ force is acceleration times mass but if I go at a high constant velocity ($900\: \mathrm{miles/hour}$) in my car for examples I have $0$ acceleration but if I ...
1
vote
2answers
162 views

Do heavier objects fall faster? [duplicate]

This question has been asked multiple times here and all over the internet yet I can't find a conclusive answer: Some claim that heavier objects do fall faster: Don't heavier objects actually fall ...
1
vote
4answers
165 views

Equivalence principle and acceleration vs a gravitational field

I picked this up on the net: Einstein came to realize the principle of equivalence, and it states that an accelerated system is completely physically equivalent to a system inside a gravitational ...
5
votes
2answers
193 views

Did people realize that gravity accelerated things before Einstein's elevator thought experiment?

I'm reading about the (very near) equivalence of gravitational mass and inertial mass in my undergrad GR course, and the text (Lambourne) describes this equivalence as the inspiration for Einstein's ...
1
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2answers
142 views

Why do orbital speeds decrease further away from the focus?

Why do orbital speeds decrease further away from the focus? A simple question, but I want to make sure I am understanding this correctly: Is it ONLY a function of the gravity well? As in, the ...
2
votes
1answer
103 views

How long would it take a projectile accelerating twice as fast as another to catch up?

Given a projectile with initial velocity $u$, and constant acceleration $a$, travelling in the one direction. How long would it take a second projectile the same as the first with the same initial ...
-1
votes
2answers
142 views

How does artificial gravity reduction (weightlessness) work on Earth?

Some of us have been to those amusement park/carnival/theme park rides where you enter some capsule/machine, and you will float, etc. There is also some other thing where you go inside a big room ...
0
votes
1answer
176 views

How did Newton find the relationship between force, mass and acceleration? [duplicate]

I have been told always that $F$ is directly proportional to acceleration. My question is that for finding such a relationship there should be source that produces desired force and in which the ...
-3
votes
1answer
39 views

Acceleration on an inclined rail [closed]

I have to use $\vec{P}+\vec{R_N}+\vec{F_f}=m\vec{a}$ with $\|\vec{F_f}\|=\mu\|\vec{R_N}\|$ to express the acceleration as $$a_{x'}=g\sin\alpha(1-\frac{\mu}{\tan\alpha})$$ The configuration is (sorry ...
0
votes
0answers
56 views

Transformation of a time-dependent acceleration to another frame

How do I transform a time-dependent acceleration between to rest frames? I was given a particular problem and while I found possibilities [1] [2] for acceleration-transformations when the acceleration ...
-2
votes
3answers
109 views

If an object fell from the moon [duplicate]

Ignoring the moons gravity, if an object sitting still (relative to the Earth, i.e. not in orbit) was dropped from the moon. How long would it take to hit the Earth?
-2
votes
2answers
233 views

Explain what happens to object in lift [closed]

In the following image,three cases have been mentioned. $N$ is the normal force acting on the object inside the lift and $mg$ is the force of attraction due to gravity. In case 1, $N = mg$. In case ...
1
vote
1answer
128 views

Reduction in gravity from photon exchange

Let's say you have two bodies at are held at rest relative to each other exchanging (real, not virtual) photons back and forth. Then we let them go (maybe push them apart slightly), so they will ...
8
votes
2answers
252 views

What is the physical meaning of $|f''(\xi )|\leq\frac{4(f(b)-f(a))}{(b-a)^{2}}$ where $f(t)$ is position as a function of time?

Here is the full problem: I was able to prove the given expression; but the interpretation part is giving me a bit of trouble. Here is my interpretation: The average acceleration in $(a,b)$, is ...
2
votes
3answers
229 views

Does GR imply a fundamental difference between gravitational and non-gravitational acceleration?

Does the equivalence principle imply that there is some fundamental difference between acceleration due to gravity and acceleration by other means (because there is no way to 'feel' free fall ...
2
votes
1answer
284 views

Force on impact in case of a free fall

In a free fall, on impact with the ground, the body experiences a massive force because of a huge acceleration since the velocity goes to 0 rather quickly. Since this force has to come as a result ...
2
votes
1answer
158 views

Is a collision with an immovable object equal to a head-on collision? [duplicate]

Scenario 1 Two identical and bilaterally symmetrical cars, driven by identical drivers in the exact center of the car and in the same body position, each traveling the same speed, collide exactly ...
1
vote
0answers
21 views

How far will the first spacecraft travel before the second one catches up to it? [closed]

A spacecraft leaves the point of origin and has a maximum acceleration of 30 m/s. It can only maintain this rate for 10 minutes before it runs out of gas and then proceeds to drift at a constant ...
0
votes
1answer
123 views

Does a heavy body move with the slightest force on a frictionless surface?

If I apply horizontal force on a body resting on the ground, my force will be opposed by the frictional force and the body will accelerate at the point where my force exceeds the force of friction = ...
1
vote
2answers
111 views

How to work out the acceleration of an object

I got given this question and im just lost. An object that weighs 25 kg experiences two perpendicular forces of 80N and 50N respectively. What's the acceleration that object gets? What i ...
0
votes
1answer
58 views

In what range the acceleration value of quantum particle lies?

According to Heisenberg's uncertainity principle, the position and velocity of an quantum particle cannot be determined simultaneously. Is it possible to determine position and acceleration ...
0
votes
4answers
171 views

Why is there no gravity in the center of a celestial body, yet there is gravity on the surface?

I've heard few explanations, but none in good detail that make it clear to those with less mathematical knowledge on the equations of complex physics. I would like to think that since you are on the ...
0
votes
2answers
49 views

How to get $t$ from $a(v)$?

I read what if we have acceleration given as a function of velocity we can calculate time as $$t(v) = t_0 + \int_{v_0}^{v} \frac{dv}{a(v)}.$$ Why?
-8
votes
3answers
118 views

What would happen if an unstoppable force hits an immovable object? [closed]

I realize that the question a rather large paradox, but I do wonder if such a thing were true what would happen. Assuming that neither of these "objects" can be destroyed by each other.
1
vote
1answer
318 views

Newtons Cradle, Collision Theory

It has come to the point in my computing program now where I have 5 swinging pendulums that are all modified at once by slider values. These values are drawn onto the from and passed through the class ...
1
vote
4answers
259 views

“Weight” of moving object in a car collision

From time to time I see safety warning about keeping loose items in your car. The last warning used a 2kg object, and claimed that if a collision occurred at $50{km\over h}$ it would have a weight ...
0
votes
3answers
109 views

I'm having trouble wrapping my head around force, and thus acceleration, diminishing with a higher velocity when using a constant power

Here is an hypothetical situation I thought about that I don't understand. Let's say I have 2 identical rockets with a fixed power. These rockets start to race in the same direction using the full ...
0
votes
0answers
217 views

A force F pushes an inclined plane M with a block on the incline; find acceleration up the incline

So there is an inclined plane of mass $M$ that is pushed with a force $F$. A block of mass $m$ is on the inclined plane that accelerates up along the inclined plane due to the pushing of $M$ by force ...
0
votes
0answers
90 views

g as a function of Theta

I slide an object down a ramp of a certain length, which is inclined at a certain angle $\theta$. It reaches the bottom in time $t$. Assuming that no forces act on the object other than gravity and ...