一 ?
一He is always a little shy.
A:What does he look like
B:How does he like it
C:What does he like
D:What is he like
如图,正六边形ABCDEF中,BA→+CD→+EF→= ( )
某校物理活动小组的同学,在课余时间想把一个普通烧水壶改装成一个家庭用电热水壶.已知改装后的电热水壶热效率为80%,壶的容积为2L.在一个标准大气压下,用此电热水壶在7min内烧开一壶初温为20℃的水.C水=4.2×103J/(kg•℃)问:
(1)烧开这一壶水需要吸收多少热量?
(2)应给电热水壶装配一个多大阻值的电热丝?
-It is on November 2nd.