(2012?西城区二模)物体A静止在水平桌面上时,对桌面的压强为p1;现将物体A悬挂在轻质杠杆的C端,当在D

2025-05-17 09:16:07
推荐回答(1个)
回答1:

(1)由杠杆平衡的条件可得,
FA×OC=GB×OD
FA=

OD
OC
×GB=
2
1
×0.5kg×10N/kg=10N;
∵p1:p2=3:1,P=
F
S

GA
GA?FA
=
p1
p2
=
3
1

故GA=15N;故A错误.
(2)mA=
GA
g
=
15N
10N/kg
=1.5kg.
ρA:ρB=
mA
vA
×
vB
mB
=
1.5kg
2
×
1
0.5kg
=3:2;故B错误;
(3)将物体浸没在水中时,因为VA=2VB,所以A受到的浮力是B受到浮力的2倍,
∵10N×OC=5N×OD
∴(15N-2F)×OC>(5N-F)×OD
因此C端会下沉;故C错误;
(4)FC×OC=(GB+2.5N)×OD
FC=7.5N×2=15N=GA.故D正确.
故选D.