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

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2answers
7 views

Why is the damping force acting on an oscillating system opposite in direction to velocity and not acceleration?

So far I know that the damping force is a frictional force that opposes motion and so it acts in the opposite direction to velocity . Bit why can't the same be said for acceleration doesn't the ...
4
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1answer
88 views

If Speed is Relative can Absolute Acceleration be Real

This is , I suppose not a good question , but I think I am missing something which confuses me in this question. So my question is - Velocity is relative. So suppose a car is moving at a speed 200 ...
0
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0answers
25 views

Frequency shift due to acceleration of the source towards the receiver [on hold]

How does acceleration of the source towards the receiver change the frequency shift? If a source of sound is accelerating towards the receiver, what should be the graph of frequency due to Doppler ...
2
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2answers
113 views

All reference frame are inertial? Where is the flaw in reasoning?

This is my first post here. I have a line of thoughts which might be wrong but I couldn't find the error. Suppose we have a point mass subjected to an arbitrary force $F$. In the lab reference frame ...
18
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8answers
10k 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?
8
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3answers
17k views
-1
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1answer
30 views

What does number of inches per day squared mean?

To give some context to this question, the Pioneer spacecraft were decelerating by: 300 inches per day squared http://www.nasa.gov/topics/solarsystem/features/pioneer_anomaly.html I cannot find ...
-5
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0answers
27 views

A car is moving with constant acceleration at 2 m/s/s. what distance will it have travelled when its velocity is 8m/s [on hold]

a car of length 3m is moving with constant acceleration at 2 m/s/s. How far will its front end be from the start point when its velocity reaches 8m/s The cars back end is on the start point and its ...
0
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1answer
36 views

Acceleration in full-swing pendulum

Consider a $360^{0}$ swing pendulum with a massless rod. If I start it from the position of unstable balance, at the very top of the circumference, according to the conservation of energy, its ...
0
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1answer
118 views

Gravitational Time Dilation vs Acceleration Time Dilation

I might be a little dense to this subject, but I would like to ask a question relating to this one ( Is gravitational time dilation different from other forms of time dilation? ) but asking if this ...
1
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2answers
49 views

Homework: Angular Acceleration from Net Torque [closed]

I have the correct answer but don't know how that is the correct one. My answers were way off which indicates I am missing something big but don't know what. Now the 4 torques are: t1=6.175, t2=....
0
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0answers
20 views

How can a lateral wind gust create a lateral acceleration for a flying object?

We had a lot of wind today and we weren't able to fly our drone with some friends If a quadrotor of mass $1kg$ flying along the positive $x$-axis at a speed of $4m.s^{-1}$, why would a wind gust ...
0
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2answers
128 views

Normal Force in Circular Motion

In the above diagram, sec1(on the left side), an object of mass $m$, after releasing from rest from a slant track, continues into a vertical circular track. At a random position on the circular track, ...
-1
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0answers
28 views

Acceleration question- student running after bus [closed]

A student is standing 50 m behind a bus. As soon as the bus begins its motion with acceleration 1 ms-2, the student starts running towards the bus wit a constant velocity u. Assuming the motion to be ...
0
votes
1answer
34 views

instantaneous velocity center

The instant center of rotation, also called the instantaneous velocity center is the point fixed to a body undergoing planar movement that has zero velocity at a particular instant of time. For ...
1
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2answers
58 views

Infinitesimal time intervals use

I've a question, that maybe will sound obvious, on the use of infinitesimal quantities. Consider the expression for the acceleration in non inertial frames. $\frac{d\vec{v}}{dt}=\frac{d\vec{v'}}{dt}...
-3
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0answers
44 views

A rock dropped onto a car windshield [closed]

The rock is made of concrete and weighs 28 grams. It is approximately 100 mm in diameter. The rock is dropped from an overpass onto a car travelling by at 88 Kph. Would this rock penetrate the ...
-6
votes
0answers
36 views

rock thrown at a car going 55 mph [closed]

forgive me. I never really studied. My argument is a rock thrown at the windshield of a car moving 55 MPH could easily kill the occupant of said car. Force = Mass X Acceleration. Right?
-3
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0answers
25 views

Deceleration question on a rocket? [closed]

I have a problem with question A in the image I have attached. I have been asked to find the deceleration of the rocket in the image attached. The working I did to find this out was the final velocity ...
1
vote
2answers
58 views

Dynamics of swinging

My husband built a 20'-high tree swing, using 3/16"-welded-link chains to suspend it approximately 2' off of the ground. To our disappointment, pumping barely gets the swing going, with little height ...
5
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2answers
8k views

Calculate speed from accelerometer

I am trying to use my accelerometer on my mobile device (smart watch to be specific) to calculate a persons arm swing speed. The data returned from the accelerometer is in $m/s^2$. Since the ...
2
votes
1answer
170 views

In perfect vacuum (no external force), if I apply a small amount of force to a body, will it continue to accelerate forever?

According to the equation $F = ma$, the greater the force applied to a body, the greater its acceleration. But in a place where there is no gravity or any other kind of external force, if I apply a ...
1
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2answers
77 views

Frame of reference in elevator

I have a conceptual question that I have trouble understanding. An object at the end of a rope is attached to the ceiling of an elevator. If the elevator is allowed to free-fall and hit the ground, ...
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4answers
113 views

Why is acceleration of expansion of space unexplained?

I didn't know how to better phrase the question so here we go. It says that the farther we see from our galaxy the faster the other object seems to be going away (accelerating). My common sense ...
-1
votes
3answers
94 views

Why does the period of a pendulum decrease in an accelerating frame? [duplicate]

If there is a simple pendulum in a non-accelerating frame with period $T_1$, it will have period $T_2 < T_1$ when placed in a frame accelerating perpendicularly to the direction of gravity. Why?
2
votes
1answer
44 views

Collision/Crumpling problem possible solution mistake

This question is from Physics for scientist and engineers , Ohanian . Two automobiles of 540 and 1400 kg collide head-on while moving at 80 kmh in opposite directions. After the collision the ...
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4answers
116 views

Measuring force of a punch

I'm trying to build a device that can mesure the force of a punch. ​ My initial plan was to build a platform with 4 springs (one at each corner) and an accelerometer in the middle. But, if the ...
-2
votes
1answer
26 views

Velocity ; Acceleration [closed]

A ball was thrown vertically upwards with a speed of 3m/s. The ball reached a highest point before falling down to the ground. What is the acceleration of the ball at the highest point? A 0m/s2 B ...
1
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3answers
63 views

An object is accelerating on a rough surface with frictional force of 10N. Is the friction doing any work on the object?

This question might look stupid to some but I am in great confusion. An object, say a box, is moving on a surface with some velocity v and is accelerating. It means that the force applied by the box ...
0
votes
4answers
86 views

Explain $\Delta x = v_0t + \tfrac{1}{2}gt^2$ please? [duplicate]

$g = \Delta v/t$, so $\Delta v = gt$. $v = v_0 + \Delta v$, so $v = v_0 + gt$. So if $\Delta x = vt$, then $\Delta x$ should be $v_0t + gt$. Why the $\tfrac{1}{2}gt^2$? I'm really confused, so this ...
1
vote
2answers
250 views

What is the effect of torque steering on a motorcycle with a long wheel base?

From experience, it appears motorcycles with a large wheelbase coupled with a long handlebar (say a modified Harley Ape Hangar) shows a noticeable tendency to veer to a side during acceleration vs a ...
0
votes
1answer
30 views

Acceleration at rest when ball is thown [duplicate]

If a ball is thrown vertically upward and it comes to rest for a moment, then its velocity decreases and becomes zero. Does its acceleration also becomes zero? If yes then how ball falls down?
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2answers
39 views

Wheel versus Sphere: Traveling Linearly Down a Track

Assume the following: A tire-like wheel and sphere are both of diameter d and mass m They are both made of the same material They are both resting at the apex of an inclined track An equal amount of ...
0
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2answers
506 views

Horizontal and vertical acceleration of a ball on a slope?

I understand that you resolve the components of the balls weight parallel and perpendicular to the slope in order to calculate the force due to gravity that actually acts down the slope. The ...
0
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4answers
111 views

Is centripetal acceleration constant?

In the case of a car traveling around a corner at a constant speed, the velocity, while constant in magnitude, is obviously changing direction and thus a centripetal acceleration directed towards the ...
4
votes
4answers
5k views

A simple derivation of the Centripetal Acceleration Formula?

Could someone show me a simple and intuitive derivation of the Centripetal Acceleration Formula $a=v^2/r$, preferably one that does not involve calculus or advanced trigonometry?
0
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2answers
247 views

Need help understanding angular acceleration due to gravity

The question asks what the angular acceleration of an uniform disc of radius $R$ rotating about an axis passing through its edge if it is released from rest with its center of mass at the same height ...
1
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2answers
91 views

Relativistic Rocket Fuel Requirements

I am trying to reconcile two different calculations of fuel for a 1g constant acceleration/deceleration trip to Alpha Centauri. One found here (http://math.ucr.edu/home/baez/physics/Relativity/SR/...
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votes
2answers
45 views

How to calculate initial acceleration of a projectile motion? [closed]

I have an object following a projectile motion, that hasn't got horizontal acceleration but only vertical -g. What is the acceleration that I have to use in the second law of motion (F = ma) in order ...
16
votes
7answers
2k views

Is there a limit to acceleration? [duplicate]

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
votes
1answer
118 views

How to draw a velocity curve from Engine power, weight and traction?

Not sure if this is the right forum but I would like to plot a velocity curve of a train, starting at 0km/h and accelerating up to a max speed. The data I have for the locomotive engines are: ...
0
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1answer
39 views

Energy required to accelerate from different reference frames

So I've recently been studying relativity a lot trying to understand it and I feel like I grasp most things conceptually but I have one issue I've been trying to understand for the last couple days ...
6
votes
5answers
9k 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 ...
1
vote
2answers
53 views

How do I find the linear components of acceleration in a pendulum?

I have managed to derive the equation of motion of a simple pendulum under the influence of gravity using the Lagrangian, but since that only tells me what the angular acceleration is, I now want to ...
-1
votes
1answer
64 views

Why is angular acceleration of a pendulum always negative?

I was trying to derive using the Lagrangian the equations of motion of a simple pendulum under the influence of gravity. Eventually, I was brought to this conclusion: $$\alpha = -(g\sinθ)/l$$ where $\...
0
votes
1answer
137 views

Can two bodies move with equal acceleration if forces acting on both are unequal?

In my textbook there is a case given that is to find acceleration and tension produced in a string passed over a frictionless pulley and attached with bodies of different masses at its ends. Now below ...
5
votes
8answers
1k views

Help understanding Bell's spaceship paradox

The problem statement of Bell's Spaceship paradox is this: Two spaceships float in space and are at rest relative to each other. They are connected by a string. The string is strong, but it ...
1
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1answer
237 views

Calculating jerk vs Fitts law for smoothness

I've tracked the movement of an input method resulting in this dataset. All data is tracked with equal intervals of 100ms. For example an iteration value of 4 means that this is the position of the ...
0
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1answer
43 views

If two cars have the same acceleration at time $t$, are the velocities of the cars the same at time $t$?

So when I look at the question logically, I reason that if I had two cars: Range Rover and BMW, at time t, I could pump the gas and make them accelerate at the same rate at 0.5 m/s^2 but I could be ...
4
votes
2answers
77 views

Acceleration of a car on Earth and on the Moon

Suppposing the same enviroment conditions and without considering the air friction a car at the start of a race would have a greater acceleration on Earth or on the Moon, or would the accelerations be ...