Answer
When a body moves in projectile motion it has two components. One of the components is a horizontal component of the velocity and another is a vertical component.
The velocity along the horizontal component does not change because there is no acceleration long horizontal component.
Whereas velocity along vertical direction keeps on changing because the acceleration due to gravity is acting on the object. At a maximum height of the projectile velocity is equal to zero.
6. f = 128.62
, T= 0.0077775 s
7. f = 2.2 *
, T = 4.545 *
s
8. 32.64 
9. 3.29 *

Explanation:
Step 1:
6.
For light and sound v = fλ
where v represents the velocity
f represents the frequency
λ represents the wavelength
λ = 2.69 m
v = 346 m/s
f = v/λ = 346/2.69 = 128.62 
Time period is the reciprocal of frequency
T = 1/128.62 = 0.0077775 s
Step 2:
7.
λ = 110 cm = 1.1 m
v = 2.42*
m/s
f = 2.42*
/1.1 = 2.2 *

T = 1/(2.2*
) = 4.545 *
s
Step 3:
8.
λ = 10.6 m
v = 346 m/s
f = v/λ = 346/10.6 = 32.64 
Step 4:
9.
λ = 5.89 *
m
v = 1.94 *
m/s
f = v/λ = 3.29 *

Answer: Reflection by clouds
Explanation:
Only some shortwave radiation from the sun reaches the Earth's surface because solar radiation is being reflected by thick clouds and thin clouds transmit the solar radiation.
About 31 % of solar radiation is reflected by clouds. The tiny water particle scatters 20-90 % of incoming sunlight giving them a bright white appearance.
12 cm x 2 cm x 3 cm = 72 cm3
Answer:
At the bottom when they hit the ground.