Answer:
Part a)

Part b)

Part c)

Explanation:
Part a)
As we know that the speed of light is given as


now the frequency of the light is given as

so we have


Part b)
Position of Nth maximum intensity on the screen is given as

so here we know for 3rd order maximum intensity

n = 3
L = 1.4 m


Part c)
angle of third order maximum is given as



Is there options? The question seems like there'd be options listed
Friction = 0.25 * m * g = 10.8
Push = m * a + Friction = 4.4 * 1.5 + 10.8
The device is an anemometer<span>
It's like 4 cups that measure the speed instead of direction
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This is a ball and socket joint.