Question

A body covers first one third of the distance with a velocity of 20m/s, the second one third with a speed of 30m/s and last one third with a velocity of 40 m/s.Then the average velocity will be

Answer 1

Answer:

3/Vavg = 1/20+1/30+1/40

3/Vavg=(6+4+3)/120

3/Vavg=13/120

Vavg=120*3/13=27.69m/sec

Answer 2

Answer:

Required average velocity is 27.69 m/s.

Explanation:

Given,

A body covers first one third of the distance with a velocity of 20m/s.

And the second one third with a speed of 30m/s

And last one third with a velocity of 40 m/s

Now we want to find average velocity,

We know,

$\frac{1}{Average \: \: velocity } = ( \frac{1}{v1} + \frac{1}{v2} + \frac{1}{v3}$ )/3

$\frac{1}{Average \: \: velocity }$=$\frac{ \frac{1}{20} + \frac{1}{30} + \frac{1}{40} }{3} = \frac{ \frac{6 + 4 + 3}{120} }{3} = \frac{ \frac{13}{120} }{3} = \frac{13}{120 \times 3} = \frac{13}{360}$

Now,

$Average \: \: velocity = \frac{360}{13} = 27.69 \: m {s}^{ - 1}$