Distance traveled by the ball is given by

here we know that
speed = 20 m/s
times = 0.25 s
now we have


so ball will travel 5 m distance in the given interval of time
Answer:
t = 1.6667 10⁻⁷ m
Explanation:
When light falls on a thin film on the surface we have two phenomena
- a change in phase when the beam passes to a medium with a higher index
- on the other hand, in the wavelength, due to the refractive index of the medium
λ = λ₀ / n
The second ray reflected from the other surface has no phase change
So the path difference between the two rays for destructive interference is
2t = m λ₀ / n
t = m λ₀ / 2n
Let's calculate
t = 1 500 10⁻⁹ / 2 1.50
t = 166.67 10⁻⁹ m
t = 1.6667 10⁻⁷ m