Answer:
Explanation:
Let T be the tension
For linear motion of hoop downwards
mg -T = ma , m is mass of the hoop . a is linear acceleration of CG of hoop .
For rotational motion of hoop
Torque by tension
T x R , R is radius of hoop.
Angular acceleration be α,
Linear acceleration a = α R
So TR = I α
= I a / R
a = TR² / I
Putting this value in earlier relation
mg -T = m TR² / I
mg = T ( 1 + m R² / I )
T = mg / ( 1 + m R² / I )
mg / ( 1 + R² / k² )
Tension is less than mg or weight because denominator of the expression is more than 1.
Yes. An object of large mass is pulled down onto a surface with a greater force than an object of low mass and, as a consequence, there is greater friction between the surface of the heavy object than between the surface of the light object.
Answer:
(D) Vega must produce more energy than HR 4374.
Explanation:
The apparent visual magnitude is defined as the luminosity of a star seen from earth. The Greek astronomer Hipparcos was the first who invent a numerical scale to describe how bright a star appear to be in the sky to the naked eye, so he gave an apparent magnitude of 6 to the faintest star in the sky and an apparent magnitude of 1 to the brigthest one. Since the arrive of the telescope era this range was expanded to negative numbers for the most luminous one.
The human eye has a logaritmical response to the luminosity of stars, so as an example, if one star has an apparent magnitude of 6 and another one has an apparent magnitude of 1, the second one will be 100 times brigther than the first one. In the other hand, for a star that has apparent magnitude of 1 it will appear to be 2.512 times brigther than a star with apparent magnitude of 2.
The apparent magnitude of a star can variate as a consecuence of the distance from earth or for its energy production.
With all these facts clear enough described above, it is easier to conclude that as the two star are at the same distance the apparent visual magnitude will depend in the energy production. In the case of Vega it has an apparent visual magnitude of 0.03, while HR 4374 has an apparent visual magnitude of 4.87. According with the scale stablished for Hipparcos, Vega will be more luminous than HR 4374. This means that Vega produce more energy than HR 4374.
The correct answer is A.
Quantum physics is the branch of science which deals with the behavior of matter and light on atomic and subatomic level. So, to understand the motion of an atom we would need quantum physics. Motion of a ball and a galaxy can be understood by Newtonian mechanics.
