Question

Sachin walks around a square plot and covers the
distance of each side at the speed of 50 m/min, 60 m/
min, 30 m/min and 20 m/min respectively. What is the
average speed of walking,​

Answer 1

Answer:

The average speed of walking is 5/9 m/s

Step-by-step explanation:

Given :

Sachin walks around a square plot and covers the  distance of each side at the speed of 50 m/min, 60 m/ min, 30 m/min and 20 m/min respectively.

To find :

the  average speed of walking

Formulae :

• Speed = distance covered/time taken

• Average speed = total distance covered/total time taken

Solution :

 Let 'x' m be the length of the side of the square plot.

Walking along the first side of the square plot,

Speed = 50 m/min = 50/60 m/s = 5/6 m/s

Let the time taken be t₁

5/6 = x/t₁

 t₁ = 6x/5 sec

Walking along the second side of the square plot,

Speed = 60 m/min = 60/60 m/s = 1 m/s

Let the time taken be t₂

1 = x/t₂

 t₂ = x sec

Walking along the third side of the square plot,

Speed = 30 m/min = 30/60 m/s = 1/2 m/s

Let the time taken be t₃

1/2 = x/t₃

 t₃ = 2x sec

Walking along the fourth side of the square plot,

Speed = 20 m/min = 20/60 m/s = 1/3 m/s

Let the time taken be t₄

1/3 = x/t₄

 t₄ = 3x sec

Average speed :

Total distance covered = x + x + x + x = 4x

Total time taken = t₁ + t₂ + t₃ + t₄

   = 6x/5 + x + 2x + 3x

   = 6x/5 + 6x

$\sf Average \ speed=\dfrac{4x}{\dfrac{6x}{5}+6x} \\\\ \sf Average \ speed = \dfrac{4x}{x\bigg(\dfrac{6}{5}+6 \bigg)} \\\\ \sf Average \ speed = \dfrac{4}{\dfrac{6+30}{5}} \\\\ \sf Average \ speed =\dfrac{4}{36} \times 5 \\\\ \sf Average \ speed=\dfrac{5}{9} m/s$

Therefore, the average speed = 5/9 ms⁻¹