All Questions

Tagged with
Filter by
Sorted by
Tagged with
-1
votes
0answers
35 views

Acceleration of an electron

I have the following question: An electron with constant acceleration is brought to the speed of 0.1 % of the speed of light along a distance of $0.1$ meters. What is the acceleration ? Along which ...
1
vote
0answers
22 views

How would one calculate velocity with respect to time in Case 2?

Case 1. : The rocket is weightless in space. It's fueled with propellant. It's wet mass is starting mass $m_s$ and dry mass final mass $m_f$. Suppose rocket's initial velociti is 0. The rocket ignites ...
1
vote
0answers
85 views

Angle between velocity and acceleration vector, and interpretation of pathway [on hold]

I just started studying mechanics, and I am stuck with the following question: $$\vec{r}(t)=a \sin(\alpha t^2)\hat{x}+b \cos(\alpha t^2)\hat{y}$$ I was asked to find the formula that expresses the ...
0
votes
0answers
35 views

Constant acceleration problem [closed]

A car starts from rest at constant acceleration of 2.0 m/s2. At the same instant a truck travelling with a constant speed of 10 m/s overtakes and passes the car. (a)How far beyond the starting point ...
0
votes
1answer
18 views

Force on a particle with uniform velocity

Let's say a particle is moving in a straight with no acceleration in an inertial frame. By Newton's laws we know that the force acting on it must be 0. But my question is, why doesn't uniform velocity ...
1
vote
2answers
85 views

How can I understand if an object stay (zero velocity) or moving with constant velocity (zero acceleration)

I thought a scenario like; lets say I am looking an object and there is nothing except this object. Is there a way to understand that if this object is stay on its position or if object moving with a ...
0
votes
1answer
28 views

Braking power and kinetic energy

I am currently stuck at a part of a problem i set myself. I am trying to create an equation for the stopping distance with respect to the force applied to the braking pads. I currently have two ...
0
votes
1answer
95 views

Relativistic mass effect

Does relativistic mass phenomena only appear while accelerating or even when the object is travelling at constant velocity (say 90% speed of light)?
18
votes
9answers
6k views

The instant an accelerating object has zero speed, is it speeding up, slowing down, or neither?

This problem is from Khan Academy. Specifically for the blue point circled in red, the answer is that at this blue point, the object is neither speeding up nor slowing down. When I think about the ...
0
votes
2answers
28 views

Intuition of Distance covered when accelerating [duplicate]

When you're moving at $5$ m/s for $1$ second, you have traveled $5$ m. When you're moving at $5$ m/s (initial velocity) and you accelerate $2$ m/s for $1$ second, you have traveled $5$ m + $1$ m (...
0
votes
4answers
102 views

What does a negative acceleration mean? Is the object slowing down, changing direction, or both?

I am confused about such things as negative velocity, acceleration, and displacement and what the negative indicates.
1
vote
2answers
68 views

Is motion smooth? [duplicate]

It's obvious that for every particle velocity is smooth i.e it cannot undergo sudden finite change in its position in infinitisiminal time. Similarly any particle's velocity cannot undergo a change ...
-1
votes
1answer
33 views

Finding tangential and normal velocity from a curve [closed]

How do you find tangential and normal velocity from a curve? I know how to find dy/dx, but I have no idea how to obtain ut and un and dv/dt.
1
vote
1answer
87 views

How does acceleration affect time dilation and length contraction?

I just studied SR and I understand how velocity affects time and length; how do they evolve during the process of reaching a certain velocity?
1
vote
7answers
96 views

Is there centripetal acceleration with velocity of 5 m/s?

So if an object is moving at $5\ \mathrm{m\ s^{-1}}$ in a circle, is it accelerating? Me and a friend are having a conversation about this.
0
votes
1answer
48 views

Hyperbolic motion with non-zero initial velocity

The equations of hyperbolic motion in a single spatial direction with initial velocity of zero are pretty easy to find given a bit of googling, such as in this answer. And while I'm too rusty at ...
3
votes
2answers
108 views

How to decelerate from velocity $v$ to stop time $t$ over distance $d$? [closed]

I'd be grateful for some help with this problem I am trying to solve. Let's say that I have an object travelling at a velocity $v$. I want that object to come to a halt in time $t$ AND travel exactly ...
0
votes
1answer
50 views

Dynamically changing acceleration of object moving towards sun due to gravity

For a collection of sci-fi short stories set in the rather near future I need an approximation of the time it would take a space ship to travel from an Earth orbit to Ceres. In a previous story of ...
0
votes
1answer
14 views

Does Horizontal Velocity remain constant when it hits a surface in a Parabolic Motion?

It is told in one of the answers that the horizontal velocity stays at 4.0 m/s after the ball bounces from the plate. Why is it still at 4.0m/s, isn't there friction or is it neglected for the sake ...
4
votes
3answers
948 views

Why isn't acceleration always zero whenever velocity is zero, such as the moment a ball bounces off a wall? [duplicate]

The answer to this homework problem is $\left(\text{D}\right) :$ I understand why we rule out options $\left(\text{A}\right)$ and $\left(\text{B}\right)$ first. However, I don't get why $\left(\...
0
votes
1answer
51 views

In the equation for acceleration (with known $v$, $u$ and $s$) why velocity is squared and displacement is multiplied by 2? [closed]

In the following equation $$a = \frac{v^2 − u^2 } {2s} ,$$ where $v$ is the final velocity, $u$ is the initial velocity, and $s$ is displacement. Why is velocity squared and displacement multiplied by ...
0
votes
2answers
43 views

Confusion on Horizontal & Vertical Components of a Parabolic Motion

This was a question I found about projectile motion, the question was what's the bike's speed when it took off. Using $S=ut + 0.5at^2$, the time taken to reach the ground is $0.505 s$, they used ...
0
votes
2answers
88 views

The maximum velocity of an object in water [closed]

Suppose we have the mass and volume of an object, like a sphere, with density less than water. We grab it under the water and leave it, so it will fly up to the surface. What will be the maximum ...
2
votes
2answers
86 views

How and why does momentum get transferred? [closed]

Let us imagine an isolated system and there are two objects of whatever masses and size. Let one object move towards the other object with constant velocity. We know, that when they collide, the ...
1
vote
2answers
231 views

Can an object have constant speed and tangential acceleration without undergoing circular motion?

Is it possible for an object to be moving with constant speed and a constant magnitude of acceleration tangent to this velocity but NOT move in a circular path? If there are other situations could I ...
17
votes
6answers
501 views

Can you jump higher if you run? If so, why? (High jumping)

I have often wondered why high jumpers can jump higher if you run. The way I see it is that you only build up horizontal speed, and since you're running on a plane, I cannot see how this speed can be ...
1
vote
2answers
37 views

Fastest hyperloop-like vehicle which a human could endure [closed]

I'm currently writing on a science-fiction novel where a transportation system like the hyperloop has been built. Now, I'm wondering how fast I can make this. Since the plot takes place on many ...
0
votes
1answer
171 views

Calculation of speed from accelerometer data

I am trying to use my accelerometer on my mobile device fitness band to find the speed of walking and running. I conducted my experiment of walking and running on treadmill where I asked a person to ...
2
votes
3answers
114 views

Possible paradox relating to acceleration, velocity, and work

I recently encountered a question that made me think of this "paradox": Imagine the following situation: There are two forces: Force 1 and Force 2. They accelerate a mass $m$ from the same initial ...
0
votes
1answer
74 views

How to Find Jerk from Discrete Velocity Data?

I have measured the velocity of an object at discrete intervals. I want to find the corresponding acceleration and jerk of the object. How do I do this with discrete values rather than continuous ...
0
votes
2answers
139 views

What would the position vs. time graph look like if the velocity vs. time graph was a curve?

In my physics class we are learning about velocity vs. time graphs and position vs. time graphs for an object. We have learned that if the object is moving with constant velocity (this would be a ...
0
votes
1answer
18 views

Average Velocity Question (isolation?)

So there is this question i've been having trouble with for the past hour. It involved a child going down a ramp on a sled at and angle theta with a total system of mass. accelerates down a hill of ...
49
votes
14answers
20k views

Why doesn't a braking car move backwards?

The net force on an object is equal to the mass times the acceleration, $F = ma$ When I brake on a (moving) car, the net force is negative, therefore causing the resulting acceleration to also be ...
0
votes
2answers
90 views

Confused with derivative and partial derivative

suppose $x=f(t)$ with a constant acceleration. Then does $\frac{\text d x}{\text d t} = \frac{\partial (x)}{\partial(t)}$ since the position in $x$ only changes with time? Then the acceleration in ...
2
votes
1answer
80 views

How does an object in space travelling at constant velocity have a net force of zero acting upon it?

If the definition of balanced forces is "two opposing forces that are equal" and an object with a net force of zero acting upon it means that the forces are balanced on the object, then it should ...
-2
votes
2answers
79 views

Why is force related to acceleration instead of velocity?

I know $F=ma$, but it's never really made sense to me. Here's an example: Hypothetical scenario- I push a bowling ball ($m = 4\,\rm kg$) sitting on the floor with $5\,\rm N$ of force. (Assume no ...
0
votes
2answers
166 views

Can acceleration at a point be non-zero if angular velocity is zero?

I have just started studying rotational kinematics.
2
votes
3answers
214 views

What is the fastest possible acceleration?

Context & Question In physics, the fastest possible speed is accepted as the speed of light. No other mass has been recorded to travel as fast as the photon. What is the acceleration of the ...
1
vote
3answers
95 views

Can average acceleration be exactly determined from discrete points separated by equal time intervals? [duplicate]

I am using the American dialect of the English language. The following definitions distinguish my question from the similar, previously asked question: https://ahdictionary.com/word/search.html?q=...
1
vote
2answers
73 views

Is the direction of average velocity the same as that of average acceleration and that of displacement?

Average velocity is defined as: $\vec{\Delta v} = \frac{\vec{\Delta r}}{\Delta t}$, and average acceleration as $\vec{\Delta a} = \frac{\vec{\Delta v}}{\Delta t}$. It is apparant from these ...
0
votes
1answer
64 views

Physical meaning of average acceleration

What is the physical meaning of average acceleration? For example, average velocity is that uniform velocity with which if an object is made to move, it will cover the same displacement in a given ...
0
votes
3answers
31 views

Why the acceleration is specified if I know the coordinates and velocity?

And I don’t understand why the acceleration can be specified if we know the coordinates and velocity
0
votes
1answer
53 views

Understanding The Average Velocity Equation

From the linear velocity function in Equation 2-11, the average velocity over any time interval (say, from $t=0$ to a later time $t$) is the average of the velocity at the beginning of the interval ($=...
1
vote
0answers
125 views

Analytical mechanics, constant angle between velocity and acceleration [closed]

A particle moves in a plane so that the angle between velocity and acceleration is constant $\alpha$. Angle $\phi$ between velocity and fixed coordinate axis varies according to a given law: $\phi(t)$....
0
votes
1answer
57 views

If two bodies move constantly but with different speed, do they move with acceleration relative to each other? [closed]

If two bodies move constantly but with different speed, do they move with acceleration relative to each other?
0
votes
1answer
26 views

Expressing average velocity in terms of acceleration

Average velocity is usually expressed as the displacement divided by the time. For example, $$v_{\text{avg}} = \frac{x(t)-x_0}{t}$$ I have not, however seen it expressed in terms of acceleration. ...
0
votes
0answers
26 views

Calculating velocity of a negative charge

From my First Year Physics Textbook: Q1 and Q2 are stationary charges of 7.5x10^-6 Coulomb each. Point P is a mobile charge of -1.6x10^-6 Coulomb, with mass 2x10^-6 kg. Based on a previous part of ...
-2
votes
1answer
120 views

Can acceleration be both the “rate of increase of velocity” and the “rate of increase of speed” in Physics?

A Dictionary of Physics (Oxford University Press) defines acceleration as: The rate of increase of speed or velocity However, from reading many other definitions it seems to me that acceleration ...
0
votes
2answers
128 views

What to call an object which is in motion but not accelerating?

I began learning about acceleration and according to the source i learned from an object only accelerates when there is change in vel. &/ direction... what i am wondering is what do you call it ...
1
vote
1answer
42 views

Distance traveled by accelerating vehicle

Let's say I'm trying to model a train accelerating from speed $v_1$ to speed $v_2$, where the train's mass $m$ and engine power $P$ is known. I would like to find both the time $t$ and the distance $s$...