Question

an athlete completes one round of a circular track of diameter 200m in 20 second what is the distance covered and the displacement at the end of 2 minutes 20 seconds​

Answer 1

$\mathfrak{\large{\underline{\underline{Answer :-}}}}$

Distance = 4400 m

Displacement = 0 m

$\mathfrak{\large{\underline{\underline{Explanation:-}}}}$

Given : Diameter of the the circular track = 200 m

Time taken to cover = 20 seconds

To find : Distance Covered displacement in 2 minutes 20 seconds

Solution : Diameter of the the circular track = 200 m

So, Radius = 200/2 = 100 m

Time taken to cover = 20 seconds

First we need to find the distance covered by an athlete

Distance covered by an athlete = Circumference of the circular track

= 2πr

= 2 × 22/7 × 100

= 44/7 × 100

= 4400/7

= 628.571429 m

So, Distance covered by an athlete = 628.571429 m

Then find the speed of an athlete

$\boxed{\sf{Speed= \frac{Distance\:traveled}{Time\:taken} }}$

$speed = \frac{628.571429}{20} \\ \\ speed = 31.4285715 \: \frac{m}{s}$

Now we can find the distance covered in 2 minutes 20 seconds

Speed = 31.4285715 m/s

Time = (60×2)+ 20 = 120 + 20 = 140 seconds

$\tt{\implies{31.4285715= \frac{D}{140} }}$

$\tt{\implies{31.4285715 \times 140=D }}$

$\tt{\implies{D=4400}}$

Therefore distance traveled in 2 minutes 20 seconds is 4400 metres.

Displacement is distance between initial position and final position

Here initial position and final position becomes same

So, Displacement = 0 m

Answer 2

$\mathfrak{\huge{\red{ANSWER}}}$

Diameter=200 m 

Radius= 100 m 

Time= 70 secs 

At the end of 1 min 10 secs he will complete 3 and half rounds 

2πr+ 2πr+ 2πr+ πr= 7πr

because 3 1/2 circles 

Distance=7πr 

= 7*22/7*100 

=2200m 

Therefore distance is 2200m 

Displacement= Diameter 

Displacement= Diameter = 200 m