Answer:
a. 10 hours
b. Approximately 4.03 km/h to shore
Step-by-step explanation:
The width of the English Channel at the narrowest point = 35 km
The speed of the current across the English Channel across the narrowest point = 2 km/h
a. The relative velocity of the swimmer north to south = 3 km/h
Therefore, the the time it would take the swimmer to swim north to south will be given as follows;
Time = Distance/Velocity = 35 km/(3.5 km/h) =10 hours
The time it would take = 10 hours
It would take 10 hours for her to cross the 35 km distance
b. Given that she has a relative velocity of 3 km/h north to south, we have;
The magnitude of her relative velocity to shore = √((Her relative velocity north to south)² + (The velocity of the English Channel east to west)²)
∴ The magnitude of her relative velocity to shore = √(3.5² + 2²) = (√65)/2 km/h
The magnitude of her relative velocity to shore ≈ 4.03 km/h