Answer:

Explanation:
Given that,
Lightning flashes one mile (1609 m) away from you.
We need to find the time it take the light to travel that distance. Let the time be t. We know that,
speed = distance/time

So, the required time is 
Answer:

Explanation:
As we know that the wave equation is given as

now we have


so we have



also we have

so we have



now we know that at t = 0 and x = 0 wave is at y = 0.19 m
so we have

so we have

Answer:
90
Explanation:
The mass number of the missing daughter nuclei can be obtained as shown in the attached photo.
-- The area under a velocity/time graph, between two points in time, is the difference in displacement during that period of time.
-- The area under a speed/time graph, between two points in time, is the distance covered during that period of time.