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

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4answers
119 views

Gravity and acceleration

I've imagined this little scenario to help me conceptualize things. Let's say we have a doughnut-shaped object with a hole whose diameter is greater than that of a sphere. Let's say that the sphere ...
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2answers
175 views

How an accelerated object sees another accelerated body in special relativity?

Assume two objects are moving with a constant acceleration $a_1$ and $a_2$, which are the measured accelerations by respective object (or constant force being applied to each of the objects). My ...
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2answers
84 views

Newton's Second Law

Newton's Second Law tells us that $\sum F = ma$. The vector sum of the forces $F$ on an object is equal to the mass $m$ of that object multiplied by the acceleration vector $a$ of the object. So ...
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2answers
103 views

Speed cannot be greater than speed of light. How about acceleration? Does it have limit?

We know that $c$ is the largest speed in the universe. How about the acceleration, does it has limit?
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3answers
217 views

Why do objects fall at the same acceleration?

I read these two posts and now I am more confused. Do heavier objects fall faster? Don't heavier objects actually fall faster because they exert their own gravity? I was going to ask: if mass ...
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2answers
43 views

Free fall question: Bill shoots his gun [closed]

Bill borrows his dad's gun and when he gets outside he fires it straight up into the air. If the bullet left the gun at 400 m/s: How long does it take the bullet to reach its highest point. I know ...
3
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4answers
390 views

Deriving $F = ma$ - Newton's Second Law of Motion

Context: In my textbook it is given: 'momentum' short for 'linear momentum': Mass = $m$, momentum is $p=mv$. In time $\Delta t$, momentum changes by $\Delta p$, the rate of change of momentum is: ...
3
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1answer
368 views

Two vehicles moving in a line with different accelerations

Let two similar vehicles starting at rest in a straight line (with a distance of $D$ between them) have time-varying accelerations in the same direction. If both of them have similar time varying ...
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0answers
52 views

Are there 'special' cases for when special relativity can be applied for accelerating bodies?

I have the following theoretical situation: A space station modeled as a ring in free space is rotating about its centre point at a high speed. I am trying to work out where time flows slower. From ...
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1answer
33 views

Acceleration Power [closed]

Suppose we have a trolley currently at rest at point A, but the motor switches on, so that it accelerates and reaches point B, at point B, the velocity is 5m/s, Distance of A-B is 10m, mass of the ...
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1answer
41 views

Kinematics with non constant acceleration II [closed]

I'm getting crazy with this problem and I think that it's pretty simple. An helicopter's helix is spinning at initial speed $w_0=200\ rpm$, all of a sudden the motor stops and it decreases its ...
2
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2answers
50 views

Acceleration of chairlift [closed]

So I'm struggling with this question, and am wondering if anyone can give me the right direction to go. For the sake of not cheating, I've changed the figures etc. I just need help on the approach. I ...
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0answers
35 views

Mario Livio's book on symmetry and the relationship between gravity and acceleration

In his book: The Equation That Couldn't be Solved Mario Livio explains the equivalence principle in laymen's terms. I took the statement on page 209: The force of gravity and the force resulting from ...
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1answer
52 views

What is a realistic launch speed of a grappling hook gun? [closed]

In The Dark Knight, at the end of the movie Batman throws the Joker off of a building and then shoots his grapple hook gun to catch him. Is 68m/s a reasonable speed for a grapple gun to shoot?
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0answers
81 views

Calculating impact velocity and time with non-uniform acceleration [duplicate]

Here goes: imagine a spacecraft with engines shut off in a free fall towards some celestial body x. let's say the distance to surface is $100 000$ $\text{meters}$. initial vertical velocity is ...
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1answer
93 views

Calculating pitch and roll with accelerations greater than +/- 1g

I'm looking to compute the pitch and roll of a device fitted with a three axis accelerometer when it is not at rest or moving at a constant velocity. Most applications I've seen so far are for ...
6
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8answers
403 views

How do we know that $F = ma$, not $F = k \cdot ma$

It seems intuitive that $a\; \propto \frac{F}{m}$, as the greater the force that is applied on an object, the greater its acceleration will be. Inversely, the greater the mass of the object, the ...
0
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1answer
118 views

Why is force dependent on acceleration, not velocity?

According to $F = ma$, force is a result of acceleration and mass, right? However, I don't understand why velocity is not used instead of acceleration. A train moving at 100 miles/hour will still ...
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1answer
56 views

Does an aircraft hover at a constant acceleration or varied acceleration?

I have a question that's bugging me. Googling it only made me more confused so I really hope someone can help me clear this. If a plane is flying up and down; or hovering (Like the x-wing scene from ...
0
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0answers
34 views

Rolling resistance

Today, my physics teacher asked the following question (and gave it as homework): How can a moving body deaccelerate both in means of center of mass and rotationally? I quickly answered that ...
0
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1answer
21 views

Inhomogeneties in gravitational acceleration at the surface of the Earth.

I am looking for data sets which clock the time and precise location of free falling bodies in a vacuum. I have been told that the acceleration of gravity is not absolutely 100% uniform, and I would ...
2
votes
1answer
124 views

Can a human body supercavitate to survive water impact?

Inspired by this analysis of a human (OK, Captain America) hitting water feet first at terminal velocity, I'm wondering if supercavitation would be possible and whether it would improve your chances ...
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3answers
76 views

Cart on Ramp with Varying Acceleration

For a lab that I have to do, the teacher has given me a data table of the displacement of a cart on a ramp after successive intervals of time. I have used this data to derive the velocities and ...
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7answers
359 views

Is there a limit to acceleration?

As we all know the speed of light is the limit at which energy/matter can travel through our universe. My question being: is there a similar limit for acceleration? Is there a limit to how quickly ...
0
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2answers
29 views

What is the acceleration of a two weights connected with wire?

Given 2 weights: m1 = 2 kg m2 = 1 kg They are connected with wire hung over stick and considering there are no wire friction. Find the acceleration of weight m1 going down. Find the (force) tension ...
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1answer
24 views

How much time would take to lift a person to 0.1m above floor of elevator? [closed]

How much time would take to lift a person to height $h$ above floor of elevator if the elevator goes down with acceleration $a$, where: $$h=0.1 \; \text{m}$$ $$ a=13 \; \text{m}/\text{s}^2 $$ How to ...
0
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2answers
57 views

Acceleration during collision with ground

For my physics class, I have to calculate an objects acceleration while it came to a stop. It was traveling at $6.26\: \mathrm{\frac{m}{s}}$ at impact, and travels a distance of $0.025\: \mathrm{m}$ ...
3
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1answer
76 views

Why is it that angular acceleration is constant in different instantaneous reference frames?

Take the following example: A rod (of length L and mass m) is held horizontally at both ends by supports. One is instantaneously removed. The specific problem is to prove that the force on the other ...
1
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1answer
70 views

Center of rotation and trajectory of a rigid body in a plane with applied *fixed* forces

This is my first question so please excuse me if my format is a bit off. Given a 2D rigid body with forces applied to it in such a way that the angle the force vector makes with the surface of the ...
6
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6answers
778 views

If an object moved 5 meters in a second, how can its velocity be 10 m/s?

I am reading the tutorial on physics classroom.com, and am at Meaning of Slope for a v-t graph. It gives data for an object experiencing an acceleration: This is the corresponding chart for the ...
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votes
2answers
124 views

How is the direction of the instantaneous acceleration determined?

I know from the text book that the direction of velocity at any point on the 2D path of an object is tangential to the path at that point and is in the direction of motion. But how would one determine ...
1
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0answers
45 views

What is the physics associated with climbing a space elevator?

Suppose you have a space elevator and you use it to lift weight to orbit. Obvious this is pulling down on the counterweight. So doesn't this mean that you need to apply appropriate acceleration ...
0
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2answers
77 views

Animating an Acceleration Vector - Acceleration of object on a crested path in gravitational field

So I was reading in Chapter 3 of my textbook, Sears & Zemanksky's University Physics with Modern Physics by Young and Freedman, 13th Edition, and the discussion took us to a definition of the ...
6
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3answers
99 views

Movement in outer space via Newton's law of every action has an equal and opposite reaction

What is more effective for travel in outer space ignoring all other factors like air radiation etc. I have a 10 kg bag of rice would I travel faster throwing the whole bag at once or throwing a grain ...
1
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3answers
75 views

What is the constant $g_0$ used for calculating the specific impulse in seconds?

Wikipedia defines specific impulse as: $$ I_\mathrm{sp} = \frac{F_\mathrm{thrust}}{\dot{m} \cdot g_0} $$ The $g_0$ is said to be the acceleration at the Earth's surface. So is it actually the ...
1
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4answers
2k views

What does the magnitude of the acceleration mean?

I am a little confused as to what the magnitude of acceleration is and what it means.
0
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0answers
22 views

Triple axis accelerometer direction-finding

Can I detect the direction of the disturbance source which propagated in the medium by waves, using only triple axis accelerometer? I guess yes, because I already have projections of all three axes ...
0
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2answers
129 views

How to estimate a person's mass from a sensor? [closed]

I'm trying to estimate the person's weight from some available sensors and I have an accelerometer, a gyrometer and a magnetometer. The triaxial accelerometer is fixed in a band in the person's ...
4
votes
2answers
208 views

If $F=ma$, how do can we experience both gravity and a normal force even though we are not accelerating

So as I sit in my chair, I experience a gravitational force pushing me into the chair and I'm also experiencing the normal force of the chair pushing back at me so I don't fall. According to Newton's ...
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0answers
270 views

Inclined plane problem

FOR THE GIVEN PROBLEM AND SOLUTION BELOW 1) The problem statement, all variables and given/known data: A student pulls on a box up an incline of 10 degrees. The student pulls with a force of 180 ...
0
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1answer
139 views

How to calculate work when a block is moving with constant velocity?

How to calculate work when a block is moving with constant velocity? As we know $f=ma$, and for constant velocity $a=0$, so $f=0$ and $w=fs=0$? Can anybody make it clear?
0
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2answers
152 views

2 bodies separated by a rope [closed]

Say you have two bodies connected by a "weightless" rope, one hanging from a ledge on a pulley (classic pulley problem). If the body that is on the surface and being pulled by the object hanging ...
8
votes
2answers
795 views

Non-Constant Acceleration due to Gravity

Recently, I had the first physics lab for my university physics course. This lab was fairly simple, as we were merely using a computer and a distance sensor to graph the position, velocity, and ...
9
votes
1answer
171 views

The most stable way of standing in a bus

Here's what's bugging me for quite a long time. Imagine the every day situation, that you are standing in a bus with your back on wall having only limited space on the floor and no handle to hold. You ...
25
votes
10answers
6k 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
66 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
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2answers
59 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
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1answer
71 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
112 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
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2answers
153 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 ...