Answer:
The wavelength of the light is 562.5 nm
Solution:
As per the question:
Order, n = 1
Slit separation, d = 
Distance from the bright fringe, y = 0.18 m
Distance between the screen and the grating, D = 0.8 m
Now,
We know from the eqn for diffraction:

n = 1
(1)
Also,
For very small angle,
:
≈ 
Using the above value in eqn (1):

Answer:
a)- 1.799 rad/sec²
b)- 17.6 x 10ˉ³Nm
Explanation:
ω₀ = 720 rev/min x (1 min/60 sec) x (2π rad / 1 rev) = 24π rad/s
a) Assuming a constant angular acceleration, the formula will be
α = (ωf -ω₀) / t
As final state of the grindstone is at rest, so ωf =0
⇒ α = (0-24π) / 41.9 = - 1.799 rad/sec²
b)Moment of inertia I for a disk about its central axis
I = ½mr²
where m=2kg and radius 'r'= 0.099m
I = ½(2)(0.099²)
I = 9.8 x 10ˉ³ kgm²
Next is to determine the frictional torque exerted on the grindstone, that caused it to stop, applying the rotational equivalent of the Newton's 2nd law:
τ = I α =>(9.8 x 10ˉ³)(- 1.799)
τ = - 17.6 x 10ˉ³Nm
(The negative sign indicates that the frictional torque opposes to the rotation of the grindstone).
Answer: The complexity of filter is the order of the filter. Greater the order of the filter, more efficient the filter is. Roll of value of one filter is 20dB/dec. So the roll-off value of 8th order filter is 160dB/dec. 8th order filter is more efficient than the second order low-pass filter.
When the elevator is going up (assuming the elevator is acceleration)
When the elevator is accelerating downwards, the total gravitational force would be larger.
If the elevator is accelerating upwards, then the gravitation force would be smaller, thus the tension in the string would be smaller.