Tagged Questions
15
votes
5answers
273 views
Does the mass point move?
There is a question regarding basic physical understanding. Assume you have a mass point (or just a ball if you like) that is constrained on a line. You know that at $t=0$ its position is $0$, i.e., ...
3
votes
2answers
106 views
Is a heavier skier faster? [duplicate]
Is it true that a heavier skier goes faster? If it is, why is that?
My intuition would be that the speed gained by a skier should be independent from its mass, since both its acceleration and the ...
0
votes
0answers
46 views
Finding an efficient strategy for walking
Let's say you are already walking at a maximally efficient combination of pace and stride (or $\omega$ and $X_0$ I guess) but you need to reach your destination faster. Should you increase/decrease ...
2
votes
2answers
162 views
Ideal 2D Unicycle Kinematics
A particle is connected to a massive wheel by a rigid rod. The wheel can roll without slipping on a horizontal surface. The particle is free to rotate around the centre of the wheel.
I believe the ...
0
votes
3answers
2k views
Difference b/w Kinetics & Kinematics w/concrete example
(I know whether I understand this or not doesn't matter much to my work & study but am just curious.)
I still can't differentiate in my head kinetics and kinematics (similar thread is found but ...
3
votes
2answers
299 views
Can these figures demonstrating the safety of “Archery Tag” arrows be correct?
There is a new sport called "Archery Tag" that involves shooting opponents with foam-tipped arrows fired out of a real bow. The official Archery Tag web site presents data that claims to show the ...
3
votes
2answers
218 views
The Double Integrator: Matching velocity and position as quickly as possible with only a limited amount of force available
If a body with mass $m$ begins at position $x_0$ with velocity $v_0$ and experiences a force that varies as a function of time $f(t)$ (and we ignore gravity, friction, and everything else that might ...
2
votes
8answers
1k views
Real world examples for projectile thrown upwards or downwards
I am preparing a physics course for high school about projectile motions. If a projectile moves with initial velocity $v_0$ in the gravitational field of the earth, the equation
$$
s(t) = 1/2 g t^2 ...
7
votes
4answers
395 views
Why does a ping pong ball change direction when I spin it on a table?
When I spin a ping pong ball on the table, it rolls forward in the opposite direction of the spin, and then eventually changes direction and rolls backward.
Here's a video demonstrating the effect.
...
2
votes
2answers
3k views
Difference between momentum and kinetic energy
From a mathematical point of view it seems to be clear what's the difference between momentum and $mv$ and kinetic energy $\frac{1}{2} m v^2$. Now my problem is the following: Suppose you want to ...
4
votes
2answers
794 views
Rigid body dynamics joints
I can't seem to find any info on connected rigid bodies by a joint. Can someone explain the basics to me? I'm trying to do a little research to find out how feasible it would be to implement 3d ...
