Question

9.
The rms speed of three molecules equals 20m/s. If the speeds of the first
two molecules are 15m/s and 25m/s, the speed of the third molecule is
(a) 10 m/s (b) 20 m/s (c) 30 m/s (d) 10 3.5 m/s​

Answer 1

Answer:

velocity of the third molecule be v= 10√3 = 17.32 m/s.

Explanation:

Given that If the speeds of the first  two molecules are 15 m/s and 25 m/s and rms speed of of three molecules equals 20 m/s. let the rms speed of the third molecule be  v m/s.

we know that

$V_{rms}=\sqrt{\frac{15^2+25^2+v^2}{3} }$

$20^2= \frac{15^2+25^2+v^2}{3}$

400×3= 225+625+v^2

v^2= 1200-900

=300

v= √300 = 10√3 = 17.32 m/s.

therefore, velocity of the third molecule be v= 10√3 = 17.32 m/s.