题目

8.The waves are observed by a child sitting in a rowboat offshore.Which of the following properties of the waves seen by the child would be greater when the boat is moving away from the beach than when the boat is stationary with respect to the beach?
I.Speed of the waves with respect to the boat
II.Frequency at which the boat encounters successive wave crests
III.Distance between adjacent wave crests
(A) I only
(B) III only
(C) I and II only
(D) II and III only
(E) I,II,and III
19.Which of the following may transmit energy from one point to another?
I.Electromagnetic radiation
II.Sound waves
III.Convection currents
(A) I only
(B) III only
(C) I and II only
(D) II and III only
(E) I,II,and III

提问时间：2021-03-19

答案

8.首先离岸的船碰到wave的frequency肯定比静止的要高啊,因此II要选然后是那个公式 速度(v)=频率(f)*波长(λ),既然波长不变,频率increase,那速度也increase嘛,因此I也要选船在离岸和wave之间的间隔没有关系啊,distanc...