They say that a rotating knife thrown is more dangerous than a knife thrown straight
I find it weird
If the knife is rotating, it will experience more air drag than if thrown straight which will also depend on plane of rotation(For some reason, I don't know, it experiences more drag if...
What I do not get is why should a stress much lower than yield point cause deformation in a material?
If temperature is high intermolecular attraction is reduced and thus even low stress can deform things.
But if it is low
Then a force lower than yield point should be less than intermolecular...
It probably calculated the MOI of the system (because it was the solution given in the booklet)
Also my MOI came out to be
(m/4)×(8a^2)÷12 + 2×(m/4)×a^2
[About x and y axes]
&&
(ma^2)+(ma^2)/3
{About z axis}
This was the question
(The line below is probably some translation of upper line in different language)
For disc it was ma^2/2
For ring it was ma^2
For square lamina it was 2ma^2/3
For rods
It was different
Please explain
Thank You🙏
I tried to solve it by integrating force from 0 to L
dF=dm.g
where dm=λdx
And then I multiplied it with velocity to get power because velocity is constant
∫(vdF)=v ∫(dF)
But the book used integration to find work done and divided it by time for power
My answer was λlgv(Option B)
Giving...
But if I spin it
I only give it an initial force
Which ceases as soon as the knife leaves my hand
So there is no force to further rotate
Then why should it rotate?
Could it be due to velocity of approach?
When a ball is thrown such that it moves in a curved trajectory in the horizontal plane, it amuses me to think of its dynamics.
In motion of a ball thrown upwards the force of gravity gives it a parabolic trajectory
However when the ball is thrown to curve and hit a target, (in the horizontal...
I have read that an electron requires certain minimum energy of threshold frequency to move an orbit
However the energy needed decreases with increase in shell number
The transition energy is reduced with each orbit
For example
The energy to shift an electron from 1st to 2nd orbit is much...
So will T1 be equal to 2T or will there be some other equations for T1?
[Because I think the string will slack if T1=2T
As m1 moves up with some a2 but the lower pulley will be stationary for T1=2T]
I think the equations should be
𝑇−𝑚2𝑔=𝑚2𝑎1
𝑚3𝑔−𝑇=𝑚3𝑎1
𝑇1−𝑚1𝑔=𝑚1𝑎2
2𝑇−𝑇1=(𝑚2+𝑚3)𝑎2
P.S.- My textbook assumes T1 = 2T.
I don't understand why that is so.