Two boats start together and race across a 74-km-wide lake and back. Boat A goes across at 74 km/h and returns at 74 km/h. Boat B goes across at 37 km/h, and its crew, realizing how far behind it is getting, returns at 111 km/h. Turn around times are negligible, and the boat that completes the round trip first wins ...

a) Which boat wins? (or is it a tie?)

b) By how much? ... km

c) What is the average velocity of the winning boat? ... km/h

Question

Physics

Pasha

7 October, 15:45

Two boats start together and race across a 74-km-wide lake and back. Boat A goes across at 74 km/h and returns at 74 km/h. Boat B goes across at 37 km/h, and its crew, realizing how far behind it is getting, returns at 111 km/h. Turn around times are negligible, and the boat that completes the round trip first wins ...

a) Which boat wins? (or is it a tie?)

b) By how much? ... km

c) What is the average velocity of the winning boat? ... km/h

+3

Answers (1)

Know the Answer?

Diva · Answer 1

74 Km/h

Explanation:

For boat A:

1 = 2l/v_1

=2*74/74 h

=2h

where = 74 wide of the lake, 1 - speed of boat A

For boat B:

2 = l/v_21 + l/v_22

= 74/37 + 74/111 ℎ

= 2.66 ℎ

where v_21 = 37 / ℎ and v_22 = 111 / ℎ speeds of boat B

boat A completes the round trip first. The difference of times equals:

∆ = 2 - 1

=2.66 ℎ - 2ℎ

=0.66 ℎ or 40 n

boat A, ∆ = 40 n

c) Average speed for boat A equals:

V = 2 / 1

=148/2 Km/h

=74 Km/h