You shine a flashlight beam toward the Moon, estimate the diameter of the beam when it reaches the Moon. Assume that the beam leaves the flashlight through a 4.0 −cm aperture, that its white light has an average wavelength of 550 nm, and that the beam spreads due to diffraction only. Express your answer using two significant figures.

12.9 km

Explanation:

θ = 1.22 * (λ/d), where

θ = angle of resolution

λ = wavelength

d = width of slit

Also, the radius of the beam on the moon is

r = lθ, were

l = distance from the earth to the moon, = 384*10^6 m

if we substitute the relation for θ, we should have

r = (1.22 * lλ) / d

Now, we substitute the values into the equation

r = (1.22 * 384*10^6 * 550*10^-9) / 0.04

r = 258 / 0.04

r = 6450 m

Diameter of the beam, d = 2r

d = 2 * 6450

d = 12900 m or 12.9 km

a.   mass number from atomic number

when two balls of the different masses are dropped from equal height, they reach the ground at the same time .this is because they experience the same acceleration.

the acceleration is independent of mass.

thus when they are dropped they will always maintain the same velocity and travel the same distance (neglect air resistance of course) at the same time.