All Questions
25 questions
12
votes
2
answers
16k
views
Understanding terms Twist and Wrench
In kinematics, physics and especially robotics, we often encounter the terms Twist and Wrench. Twist is (LinearVelocity, AngularVelocity) and Wrench is (Force, Torque). The reason I'm confused is I ...
- 505
3
votes
2
answers
4k
views
Elastic collision between two circles [duplicate]
I am trying to calculate the final velocities of two equal mass 2-dimensional circles after an elastic collision. I have tried to figure it out using formulas I know from high school physics, but ...
user99752
3
votes
1
answer
137
views
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
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
2
votes
2
answers
1k
views
Does the position-time graph have to be a smooth function?
If at some time $t$ there were a discontinuity in the velocity-time graph, then the acceleration would be infinite at $t$. So intuitively, it seems that the velocity-time graph must be continuous. I ...
- 121
2
votes
3
answers
436
views
Can something have momentum but not velocity?
The idea of momentum is fundamental, even more fundamental than velocity or mass. But I was wondering can momentum exist without velocity, since momentum can exist without needing mass?
Thinking ...
- 1,376
1
vote
2
answers
2k
views
Direction of velocity and displacement
Do velocity and displacement always have the same direction? I know this seems like a silly question to ask, but I'm having a hard time coming up with any counter examples, and I'm not able to prove ...
1
vote
1
answer
151
views
Angular velocity by velocities of 3 particles of the solid
Velocities of 3 particles of the solid, which don't lie on a single straight line, $V_1, V_2, V_3$ are given (as vector-functions). Radius-vectors $r_1, r_2$ from third particle to first and second ...
- 113
1
vote
2
answers
113
views
If hypothethically a car tries to go in two different directions at the same time, which direction will it end up going?
When we add two vectors(A and B), we get one resultant sum vector(C).
i.e. adding two different directions gives us one resultant direction.
So in the same way if a hypothetical car was trying to go ...
- 43
1
vote
1
answer
37
views
Determine the velocity by a projectile motion [closed]
A snowball rolls from the roof of a large barn that has a downward slope of 20 °. The roof end is 15.0 m above the ground and the snowball has a speed of 6.00 m / s when abandoned from the roof. At ...
- 13
1
vote
3
answers
2k
views
How is final velocity negative when acceleration is in positive direction?
When a body starts from rest and starts accelerating in positive direction and moves certain positive distance, its final velocity is given by :
$$v^2 = u^2 + 2as$$
Solving it gives two values of $v$, ...
- 71
0
votes
5
answers
1k
views
Do released objects take the direction and speed of their parent frame's velocity, or just the parent frame's speed component?
Context: I'm working on a space game. I noticed that an unpowered object fired from a strafing spaceship appeared, as the released object moved, to curve in the direction the ship was strafing. This ...
0
votes
2
answers
212
views
Query into the cumulative velocity of mounted platforms
Consider throwing a stone at an object from rest, it travels at Vms-1. Now throw that stone whilst running at Ums-1. It seems in the latter scenario the total speed of stone is V + U. Now imagine ...
- 227
0
votes
4
answers
213
views
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
0
votes
2
answers
55
views
Is the way of determining my angle of vector wrong or am I using the wrong formula for calculating magnitude of resultant? [closed]
i) Two balls A and B are simultaneously projected from top of building at 10m/s upward and 20m/s downward. Find distance between them after 3s? (Answer: 90m)
There are two magnitude of resultant ...
- 111
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 ...
0
votes
2
answers
694
views
How to maintain the same initial velocity in trials with projectile motion experiment?
If I would like to experiment with projectile motion to determine the relationship of launch angle and horizontal range (for instance, I would throw a ball multiple times from a height with varying ...
user282164
0
votes
1
answer
375
views
Angular acceleration of ball when falling [duplicate]
Why is it assumed that angular acceleration is 0 when a ball is midair after rolling off a surface with constant velocity?
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
0
votes
0
answers
85
views
Cartesian coordinate velocity and generalized coordinate velocity
use $x_k$ to denote the kth component of cartesian coordinate, and $q_k$ to denote the generalized coordinate.
Taking the derivate of $x_k(q_1,q_2,q_3,t)$ w.r.t. time, we have
$$\frac{d x_k(q_1,q_2,...
- 105
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
2
answers
97
views
How to decide which velocity is bigger in a collision before writing velocity of approach and velocity of separation?
My teacher said that velocity of separation is $V_1$- $V_2$ where $V_1$ is greater than $V_2$ and said same for velocity of approach. The problem is how would you determine which velocity is greater ...
- 5
-1
votes
4
answers
100
views
Understanding velocity as a vector quantity [closed]
Why is velocity classified as a vector quantity. Can it be explained by the same way as force referring to the Phys.SE post Where am I confused about force addition?
- 9
-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 ...
-4
votes
1
answer
69
views
Is it possible for a point-like system to behave like $x(t) = \frac{t}{2}\log(t^2)$ near $t=0$? (infinite speed) [closed]
Is it possible for a point-like system to behave like $x(t) = \frac{t}{2}\log(t^2)$ near $t=0$? (infinite speed)
I know beforehand that relativity theory forbids anything with mass from travel faster ...
- 103