All Questions
5 questions
3
votes
3
answers
278
views
Do there exist motions in which the second derivative of position is not well defined?
After some thought today, I realized that all the power of Newton's laws is fundamentally rooted in the fact that $\frac{d^2 x}{dt^2}$ is a sensible thing to write i.e: there exists a function $x$ ...
- 8,040
3
votes
1
answer
74
views
Newton's axioms and collision
Newton's axioms for point particles states that the velocity of a point particle is differentiable. However when two object collide there is a jump in their respective velocities. So is "ideal" ...
1
vote
1
answer
141
views
What is the difference between zero and an infinitesimal number?
In a standard Atwood machine physics problem, the string going over the pulley is considered massless. So does that imply mass = 0 or mass = dm? General question: what is the difference between 0 and ...
- 87
0
votes
0
answers
38
views
Making the sloppy time-reversal transformation precise
I'm reading Harbovsky and Susskind's The Theoretical Minimum Vol I.
In Lecture 3: Dynamics, under Aristotle's Law of Motion is mentioned Aristotle's (fallacious) law $F(t) = m {dx\over dt}$. Later, ...
- 1,999
-1
votes
3
answers
180
views
Avoiding a confusion with dot product
Some days ago I have asked a question about a formula for power, many generous people have answered my question and clarify for me that the correct formula of work is
$$\mathrm{d}W= \mathbf{F}\cdot \...