18
votes
Why do race cars accelerate faster than jets?
When a jet fighter is at the beginning of its take-off roll, its engine accelerates a (relatively) small amount of air to a very high speed. This is not an efficient way to produce thrust at low speed....
- 504
6
votes
Accepted
Direction of centripetal acceleration
I suppose the derivation that you are referring to is set up in a similar way to that shown below:
If this is the case it is necessary to understand that the quantities such as
$\Delta s$, $\Delta \...
- 504
5
votes
Why does an accelerated clock record fewer events?
No, you misunderstand what is happening. The difference in time is a consequence of the geometry of spacetime.
It might help to consider an analogy with 3d space. Suppose you drive your car in a ...
- 26.6k
4
votes
Value of $g$ in frictionless surface
The value of $g$ does not change in the absence of air resistance. What changes is how much of the gravitational force results in acceleration. With air resistance, some of the gravitational force is ...
- 94
4
votes
Why does an accelerated clock record fewer events?
Your first mistake is here: "The clock is accelerated and its tick rate is observed to decrease by all observers relative to the tick rates of their local clocks."
After a clock changes ...
- 16.2k
3
votes
Direction of centripetal acceleration
Filling in some information about limits from Nathan's answer (+1).
In the diagram, you calculate the centripetal acceleration by using the velocities at A and B. This tells you about the rate of ...
- 42.6k
3
votes
Why do race cars accelerate faster than jets?
Frame challenge: Why should the jet accelerate faster? This just seems to be an assumption from you.
Acceleration is given by force divided by mass. It's that simple. Whichever vehicle has the larger ...
- 141
2
votes
Accepted
How does a rocket burning fuel at a constant rate affect its acceleration?
Let us first take a visual, graphed approach to your question.
$$
\begin{equation}
F = ma \tag{1}
\end{equation}
$$
Hence rearranging $ (1) $ gives:
$$
a=\frac{F}{m}
$$
Note that m represents the ...
- 94
2
votes
Angular Acceleration of a rigid body about different axes
the velocity at Point P
$$\vec v_P=\vec v_1+\vec\omega_1\times \vec r_1=\vec v_2+\vec\omega_2\times \vec r_2\tag 1 $$
with
$$\vec v_2=\vec v_1+\vec\omega_1\times \vec r=\vec v_1+\vec\omega_1\times (\...
- 12.7k
2
votes
Direction of centripetal acceleration
To understand the situation in the limit required by the definition of acceleration, it is probably better to use analytic formulas instead of pictures.
The following time dependence of coordinates ...
2
votes
Do gravitational waves cause matter to radiate?
Let us assume that our gravitational waves are described by a linearized Einstein equation, so that the metric is of the form
$$
g_{\mu\nu} = \eta_{\mu\nu} + h_{\mu\nu}
$$
Where $\eta_{\mu\nu}$ is the ...
- 1,968
1
vote
Accepted
Effect of a spring’s mass on acceleration in a mass-spring system
Assume that the $x$-axis starts at the point mass $M$ and extends down the spring, whose length is taken to be $L$.
Draw a free-body diagram of an infinitesimal portion of the spring, and sum the ...
- 27k
1
vote
Accepted
Steep missile turn during launch?
The first thing to note is that a cruise missile is actively controlling its trajectory - it is very much not like a firework rocket, where you just light the fuse and stand back.
The reason for the ...
- 57.5k
1
vote
Why does an accelerated clock record fewer events?
This had me confused:
The clock also continuously records its readings so that at the end of the experiment there is a single record upon which all observers will agree
IMO, That's an unnecessary ...
- 15.6k
1
vote
Why does an accelerated clock record fewer events?
The physical properties like frequencies of atoms are of course valid in the proper time of the object.
One well known effect is the detection of muons. They are formed about twelve thousand meters in ...
- 16.8k
1
vote
How does a rocket burning fuel at a constant rate affect its acceleration?
If you decrease $x$ at a constant rate, $\frac 1x$ does not increase at a constant rate.
As the acceleration is basically similar to this division (constant force and decreasing mass), its behavior is ...
- 41.9k
1
vote
Do gravitational waves cause matter to radiate?
It depends on your exact setup but in theory you could arrange for gravitational waves to generate electromagnetic radiation, however in practice I don't think this scenario is very plausible to occur ...
- 52.2k
Only top scored, non community-wiki answers of a minimum length are eligible