Question

An athlete completes one round of a circular track of diameter 200 m in 40 s. What will be the distance covered and
the displacement at the end of 2 minutes 20 s?

Answer 1

Answer:

We know that, velocity along a circular path

=

Circumference

time

⇒

v

=

2

π

r

40

s

⇒

v

=

2

×

3.14

×

100

m

40

s

⇒

v

=

628

m

40

s

⇒

v

=

15.7

m

/

s

(a) Distance after 140s

We know that,distance=velocity ×time

⇒ distance=15.7m/s ×140 s = 2198 m

(b) Displacement after 2 m 20 s i.e. in 140 s

Since,rotatin in 40 s=1

Therefore, rotation in

1

s

=

1

40

∴ rotation in

140

s

=

1

40

×

140

=

3.5

Therefore, in 3.5 rotations athlete will be just at the opposite side of the circular track, i.e. at a distance equal to the diameter of the circular track which is equal to 200 m.

Therefore, Distance covered in 2 m 20 s = 2198 m

And, displacement after 2 m 20 s = 200m

Answer 2

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