Answer:

Explanation:
From the question we are told that:
Distance of wall from CD 
Second bright fringe 
Let
Strontium vapor laser has a wavelength \lambda= 431 nm=>431 *10^{-9}m
Generally the equation for Interference is mathematically given by

Where



The acceleration of gravity is inversely proportional to
the square of the distance from Earth's center.
The acceleration of gravity is 9.8 m/s² on the Earth's surface ...
6380 km from the center.
If the acceleration of gravity at 'h' is 4.9 m/s² ... 1/2 of what it is
on the surface, then the distance from the center is
(6380 x √2) = 9,023 km (rounded) ,
and 'h' is the distance above the surface
= (9,023 - 6,380) = 2,643 km (rounded) .
D. Velocity because it describes a speed and direction
Answer:
2,400kg * m/s
Explanation:
You are missing some information in the question but the rest could be found some where else.
The question gives the masses and starting velocity of each car.
Car 1: m = 600kg and sv = 4m/s
Car 2: m 400kg and sv = 0m/s
Find the momentum of both cars.
Car 1: 600 * 4 = 2400
Car 2: 400 * 0 = 0
Add both.
2400 + 0 = 2400
Best of Luck!