Let her initial velocity be U.
Let the width of the river be W.
She swims 3/5 the width of the river at U.
Remainder width = (1 - 3/5) = 2/5.
She then swims 2/5 the width with velocity U/2.
Average Speed = (Total Distance Traveled) / ( Total Time Taken).
Distance = Speed * time
time = Distance / Speed.
Time in first trip: = (3/5)W / U = 0.6W/U.
Time in second trip = (2/5)W / (U/2) = 0.4W / 0.5 U = 0.8W/U
Total Distance Traveled = W, width of the river.
Average Speed = W / (0.6W/U + 0.8W/U) = W / (1.4W/U)
= W * U / 1.4W
= U/1.4
= U * 10 / 14
= (5/7) U.
Therefore Average speed is (5/7) of the initial speed.
Answer:
Also 0
Explanation:
Since average speed of an object is that object's displacement over a unit of time, when an average speed is 0, its displacement over a unit of time must also be 0. When an average speed is not 0, then its displacement over a unit of time is also not 0 for that interval.
Sample a is an acid. Ex. Acid rain
Sample b is very weak acid , almost neutral ex. Milk.
