Miss Hill taught physics in a school in London.She was explaining to one of her classes about sound,and she decided to test (测验) them to see haw well she had been in her work.She said,"Now,I have a sister in Washington.If I was call?ing her on the telephone,and at the same time you were 25 metres away,and listened to me from the other side of the street,who would hear me first,my sister or you?And why?" :The cleverest boy answered at once,"Your sister

Miss Hill taught physics in a school in London.She was explaining to one of her classes about sound,and she decided to test (测验) them to see haw well she had been in her work.She said,"Now,I have a sister in Washington.If I was call?ing her on the telephone,and at the same time you were 25 metres away,and listened to me from the other side of the street,who would hear me first,my sister or you?And why?" :
The cleverest boy answered at once,"Your sister,Miss Hill,because electricity (电) travels faster than sound waves (声波)."
"That's very good," Miss Hill agreed.But then one of the girls put up her hand,and Miss Hill said,"Yes,Kate?"
"I don't agree," Kate said."Your sister would hear you earlier because when it's.11:00 here,it is only 6:00 in Washington."
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