All Questions
22 questions
0
votes
4
answers
213
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Why acceleration is not always parallel to velocity but velocity is always parallel to displacement? [closed]
Velocity is derivative of displacement :
$$\vec v=\frac{\mathrm {d\vec r}}{\mathrm dt}$$
And acceleration is derivative of velocity.
$$\vec a=\frac{\mathrm {d\vec v}}{\mathrm dt}$$
Given that their ...
- 325
2
votes
0
answers
80
views
Equation of Motion of Rigid Body Represented by Twist and Derivative of Twist
This question is an extension of question Understanding terms Twist and Wrench.
Assuming there is a rigid body with body twist denoted as $\mathcal{V}_{b}=\left(\boldsymbol \omega_{b}, \boldsymbol v_{...
- 21
0
votes
1
answer
94
views
Velocity and acceleration of a ball shot uphill [closed]
Consider a ramp of length $100$ m and with a height of $10$ m. At the base of that ramp we're shooting a ball of mass $12$ kg uphill. Let's say the ball has a speed of $1$ m/s at $1$ m uphill. How can ...
- 103
1
vote
1
answer
63
views
Determining the trajectory of a particle given the tangential and normal accelerations
Consider a particle with tangential and normal accelerations $\vec{a_T}(t)$ and $\vec{a_N}(t)$ respectively ($t$ is time). If the initial velocity and position vectors are both $\vec{0}$, how can the ...
- 15
-1
votes
1
answer
455
views
How to find the direction of acceleration if an object is changing its direction of velocity but not magnitude then how we can find the direction
I am new at this topic so please do mind if my question doest make sense to you.I am trying to find out that what will be the direction of acceleration if object changes Direction of velocity but not ...
0
votes
1
answer
35
views
Displacement on trip around globe?
I am tutoring in physics, specifically in kinematics and uniform acceleration, and I thought it would be fun to find the time it would take for a car to drive around the globe given an initial ...
-2
votes
1
answer
116
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Regarding Uniform Acceleration [closed]
Please give some basic intuition or hint to solve this question. I'm getting stuck.
The star of a distant solar system explodes as a supernova. At the moment of the explosion, a
resting exploration ...
- 1
3
votes
1
answer
137
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Average Velocity ($\vec{\bar{v}}$) Intuition and Analogy for Non-Uniform Acceleration
Background
So I was trying to make as much sense out of kinematics through intuition after having taken my first semester of university physics, and I've stumbled onto a dillema that I can't seem to ...
- 66
3
votes
3
answers
444
views
Velocity after applying a force in the vacuum
I’m sorry for so simple question, but I just need to be sure.
I understand, that the changing of the speed occurs only when the force is applied, I understand that if one punch a ball in the free ...
- 143
1
vote
1
answer
76
views
Determining acceleration in order to meet a space-time-velocity reservation
An Example
A train on a single line track is told to be at position $x_{res}$, at time $t_{res}$, and to be moving at exactly $v_{res}$ when it hits that point. Where $_{res}$ denotes the reservation....
- 11
0
votes
1
answer
1k
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.
0
votes
1
answer
57
views
Change of variable in function
Suppose I have a function $h(\theta)$ measuring the height of a piston, with $\theta = \omega t$. I would like to know the vertical acceleration of this piston as $\omega$ changes at the point $\theta ...
- 1,420
3
votes
2
answers
127
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 ...
- 31
0
votes
2
answers
15k
views
The human body can survive an acceleration trauma incident (sudden stop) if the magnitude of the acceleration is less than [closed]
The human body can survive an acceleration trauma incident (sudden stop) if the magnitude of the acceleration is less than 250 m/s². If you are in an auto- mobile accident with an initial speed of 105 ...
-1
votes
2
answers
2k
views
Calculating the acceleration that can be done before stopping is impossible in a given distance
My basic problem is this:
In a frictionless environment, I have an object traveling at a known speed that has a known maximum deceleration rate and a known distance to move before it must stop. I ...
- 1
1
vote
2
answers
1k
views
Why is my proof for centripetal acceleration given uniform motion wrong?
I was trying to make my own proof for centripetal acceleration (a = (v^2)/r).
I took two points along the path of motion A and B, which are a distance (along the circle) of half the circumference of ...
- 199
0
votes
2
answers
2k
views
Average acceleration: why I am getting different results?
Let's consider a simple school problem.
A car starts moving during 3 seconds with a constant acceleration of 1 m/s^2.
Then it stops accelerating and moves 3 seconds more with a constant speed.
Find ...
- 31
2
votes
2
answers
8k
views
Half-atwood machine with accelerating pulley
This is a follow-up to my previous question, in which I am now trying to calculate the acceleration of the cart (as before, the block surfaces are frictionless). The mass $m_2$ is attached to $M$ via ...
- 1,605
-13
votes
3
answers
3k
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?
- 305
1
vote
0
answers
59
views
One dimensional motion with changing acceleration. Falling to a large body from a great distance [duplicate]
Possible Duplicate:
Radial fall in a Newtonian gravitational field
My math and physics are rusty. I am trying to calculate the time an object takes to fall to a large body. Before you answer $1/...
- 119
1
vote
2
answers
153
views
Acceleration: Value Disparity?
If we consider a ball moving at an acceleration of $5\ \mathrm{m\ s^{-2}}$, over a time of 4 seconds, the distance covered by the ball in the first second is $5\ \mathrm m$. In the 2nd second will $5\ ...
- 383
0
votes
3
answers
10k
views
In a 2D problem with a thrown object, why is the acceleration along the x-axis equal to 0?
I'm starting Physics, and I don't understand why the acceleration along the x-axis is zero for an object thrown near the surface of the Earth. This may be problem specific, but I wouldn't know since I ...
- 101