Answer:
73.5 m/s
Explanation:
The position of the first ball is:
y = y₀ + v₀ t + ½ at²
y = h + (0)(18) + ½ (-9.8)(18)²
y = h − 1587.6
The position of the second ball is:
y = y₀ + v₀ t + ½ at²
y = h + (-v) (18−6) + ½ (-9.8)(18−6)²
y = h − 12v − 705.6
Setting the positions equal:
h − 1587.6 = h − 12v − 705.6
-1587.6 = -12v − 705.6
1587.6 = 12v + 705.6
882 = 12v
v = 73.5
The second ball is thrown downwards with a speed of 73.5 m/s
Process is called condensation and it happens when heat is removed from gaseous system.
Explanation:
It is given that,
The thinnest soap film appears black when illuminated with light with a wavelength of 535 nm, 
Refractive index, 
We need to find the thickness of soap film. The soap film appear black means there is an destructive interference. The condition for destructive interference is given by :
t = thickness of film
m = 0,1,2....
= refractive index
For thinnest thickness, m = 1
Hence, this is the required solution.
To answer this question, we would need the formula for the kinetic energy which is Kinetic Energy = ½ x m x v^2
Where the following means: m is the mass of the object and v is the velocity
So At 7 m/s: Kinetic Energy = ½ x 5 x 7^2 = 122.5 J is the answer
