PeroK's latest activity
-
PeroK reacted to Hornbein's post in the thread High School Why higher speeds need more power if the backward force is the same? with
Skeptical.
Consider wall sits, something that serious skiers do. Lean against a wall as though sitting in a chair, held up only by friction... -
PeroK reacted to PeterDonis's post in the thread Graduate Couldn't the cosmological constant also have some sort of "dynamics"? with
Like.
It's straightforward to write down the model; indeed doing that is an exercise in some advanced GR textbooks. The usual way is to use a... -
PeroK replied to the thread High School Why higher speeds need more power if the backward force is the same?.There is such a thing as hill racing, where athletes run up and down mountains. On the uphill, however, only the top athletes do more...
-
PeroK reacted to Hornbein's post in the thread High School Why higher speeds need more power if the backward force is the same? with
Haha.
Actually running up stairs is easier. I learned it when I was a kid and have practiced it my whole life. It appears I am the only... -
PeroK reacted to Baluncore's post in the thread High School Why higher speeds need more power if the backward force is the same? with Like.
The rate of energy flow, that an engine can convert, is its power rating. Kinetic Energy; Ek= ½⋅m⋅v² Velocity; v = √ ( 2 ⋅ Ek / m ) As...
-
PeroK replied to the thread High School Why higher speeds need more power if the backward force is the same?.A bike is a complicated machine. As the pedals speed up, it becomes harder to maintain the force. Without changing gear, you end up...
-
PeroK replied to the thread High School Why higher speeds need more power if the backward force is the same?.There are a lot of people who think that applied force remains constant as speed increases. They see applied force as the fundamental...
-
PeroK replied to the thread High School Why higher speeds need more power if the backward force is the same?.Consider an object falling in vacuum under a constant gravitational force. The rate that kinetic energy is gained by the object...
-
PeroK reacted to wrobel's post in the thread Undergrad Confusion about derivation of equation in Gregory with
Informative.
The following formulas are useful. Try to get them by yourself. Suppose we have a curve ##\boldsymbol r=\boldsymbol r(s).## And let a a... -
PeroK replied to the thread Undergrad Confusion about derivation of equation in Gregory.The way I would look at it, he actually gets equation 1.13 from 1.14 (using Taylor expansions). I.e.: $$\kappa^{-1} \sin(\kappa s) =...
-
PeroK reacted to Sam Six's post in the thread Systems Thinker Exploring Foundations of Physics with Like.
Thank you, that’s very helpful and completely fair. Coming from a systems-thinking background, I’m very aware that real understanding...
-
PeroK replied to the thread Systems Thinker Exploring Foundations of Physics.:welcome: Generally, it's very difficult to follow developments in theoretical physics without being able to solve at least advanced...
-
PeroK replied to the thread Undergrad A question about variables of integration.I don't think you have to make any substitutions. In general, if: $$f(t) = \frac{d}{dt}g(t)$$Then, by the fundamental theorem of...
-
PeroK reacted to sophiecentaur's post in the thread Undergrad Is calling fictitious forces "not real" just about terminology? with Like.
Absolutely true. But we do not think and experience life in equations. There is an 'arrow' of causality as there is an arrow of time...
-
PeroK reacted to Ibix's post in the thread Undergrad Is there anything inside a black hole? with Like.
It's worth noting that this is an over simplification, one which contributes to the confusion around black holes (IMO) by providing a...