Question

3.
A particle travels first 'X' metre with speed
'Vm/s, next '2x'm with speed '2vm/s, next '3x'm
with speed '3v'm/s. The average speed of the
particle is
(1) v
(2) 4v
(3) 20
(4) 9V​

Answer 1

Answer:

First find total time

$time = \frac{distance}{speed}$

$\frac{x}{v} + { \frac{2x}{2v} } + \frac{3x}{3v} = \frac{3x}{v}$

total distance

$= x + 2x + 3x = 6x$

So average speed

$= \frac{6x}{ (\frac{3x}{v} )} = 2v$

Answer 2

let time for all three part be t1 ,t2,t3,

• t1=x/v
• t2=2x/2v=x/v
• t3=3x/3v=x/v

so total distance traveled

= x+2x+3x =6x

and total time =3 (x/v)

so, total distance /total time

=6x/3x/v= 2v

hence the average speed is 2V.