Two objects A and B have masses mA and mB respectively. The ratio of mA to mB is 1:4. The ratio of kinetic energy possessed by A to that of B is 4:1. Find the ratio of A's spped to B's speed.作者: shizuki_tsuyuki 時間: 5/8/2008 06:52 PM mA/mB=1/4
0.5 mA (vA)^2:0.5 mB (vB)^2=4:1 mA(vA)^2/mB(vB)^2=4 1/4* (vA)^2/(vB)^2=4 (vA)^2/(vB)^2=16 vA/vB=4 vA:vB=4:1作者: today1314 時間: 7/8/2008 12:00 AM 我唔明點解0.5 mA (vA)^2:0.5 mB (vB)^2 會 =4:1 你可唔可以解釋吓??唔該作者: sapphire 時間: 7/8/2008 12:22 AM The ratio of kinetic energy possessed by A to that of B is 4:1.
看不明這句嗎?
K.E. in A : K.E. in B = 4 : 1 K.E. = 1/2 m(v^2)
so that: 1/2 mA (vA)^2 : 1/2 mB (vB)^2 = 4 : 1
where mA = mass of A vA = velocity of A mB = mass of B vB = velocity of B