Complete Question
One day, after pulling down your window shade, you notice that sunlight is passing through a pinhole in the shade and making a small patch of light on the far wall. Having recently studied optics in your physics class, you're not too surprised to see that the patch of light seems to be a circular diffraction pattern. It appears that the central maximum is about 2 cm across, and you estimate that the distance from the window shade to the wall is about 5 m.
Required:
Estimate the diameter of the pinhole.
Answer:
The diameter is 
Explanation:
From the question we are told that
The central maxima is 
The distance from the window shade is 
The average wavelength of the sun is mathematically evaluated as

Generally the visible light spectrum has a wavelength range between 400 nm to 700 nm
So the initial wavelength of the sun is 
and the final wavelength is 
Substituting this into the above equation


The diameter is evaluated as

substituting values


Answer:
b is the answer of that question answer sapai
The net force on the block perpendicular to the floor is
∑ F[perp] = F[normal] - mg = 0
so that
F[normal] = (5 kg) g = 49 N
Then
F[friction] = 0.1 F[normal] = 4.9 N
so that the net force parallel to the floor is
∑ F[para] = -4.9 N = (5 kg) a
Solve for the acceleration a :
a = (-4.9 N) / (5 kg) = -0.98 m/s²
Starting with an initial velocity of 5 m/s, the box comes to a stop after time t such that
0 = 5 m/s - (0.98 m/s²) t
⇒ t ≈ 5.1 s
Answer:

Explanation:
Here as we know that total angular momentum is always conserved for child + round system
so here by angular momentum conservation we have

here we have
(inertia of boy)


now we have



