Question

A boat sails along the shore. To an observer, the boat appears to move at a speed of 22 m/s, and a man on the boat walking forward appears to have a speed of 23.1 m/s. How long does it take the man to move 3 m relative to the boat?

Answer 1

 the boat is moving at 22 m/s while the man is moving at 23.1 m/s. That means the man, relative to the boat, is moving at 23.1-22 = 1.1 m/s. v=d/t, so t = d/v --> t = 3/1.1 = 2.7 s

Answer 2

2.7 s

Step-by-step explanation:

The boat moves (relative to the observer) at 22 m/s, while the man moves at 23.1 m/s (still relative to the observer), therefore the speed of the man (relative to the boat) is

`v_m' = v_m - v_b=23.1 m/s-22 m/s=1.1 m/s`

The time the man takes to walk 3 m (relative to the boat) is equal to the ratio between the distance (3 m) and his speed, relative to the boat:

`t=(d)/(v_m')=(3 m)/(1.1 m/s)=2.7 s`