Answer:
The correct answer is 231 Mpa i.e option a.
Explanation:
using the equation of torsion we Have

where,
= shear stress at a distance 'r' from the center
T = is the applied torque
= polar moment of inertia of the section
r = radial distance from the center
Thus we can see that if a point is located at center i.e r = 0 there will be no shearing stresses at the center due to torque.
We know that in case of a circular section the maximum shearing stresses due to a shear force occurs at the center and equals

Applying values we get

Answer:
Work done,W= 250J
Displacement , s = 60
We know that, Work done = Force x displacement
i.e , W = Fxs
250 J = F x 60m
F = 250/60
=4.16 N
Hence , 4.16 N of Force is applied on the body.
Answer: C. Stars have different colors based on their temperature
Explanation: The stars have different colors because the further away from earth the stars physical appearance may change.