Answer:
(i) Diameter of circular track = 200 m
Radius
of circular track
Circumference
of circular track
(1)
Total
time given = 2 min 20 s
According
to question, athlete takes 40 s to complete one round.
Distance
covered in 40
(Distance
covered in one round is equal to the circumference of the track).
Distance
covered inor distance
covered in
(1)
(ii)
As per the question, athlete completes one round in 40 s, i.e, after 40 s,
athlete comes back to its initial position or after 40 s his displacement is zero.
Similarly after 120 s ,
his displacement is zero.
(1/2)
Displacement
after 2 min 20 s or 140 s
=
Displacement after 20 s. (1)
(After 120 s
(2 min), displacement is zero.)
(1/2)
In
20 s, athlete will cover half the circular track from A to B (in 40 s one
complete round is taken, so in 20 s half round will be taken).
Displacement
after 20 s = AB
(Initial
position is A and after half round, final position is B)
=
Diameter of circular track
=
200 m (1)
Or
(i)
Consider a body which starts with initial velocity u and due to uniform
acceleration a, its final velocity becomes after time t. Then, its average
velocity is given by
Average
velocity
(1)
The
distance covered by the body in time is given by
Distance,
s = average velocity time
or
or
(ii)
We know that,
?(i)
Also, (1)
Substituting
the value of t in Eq. (i), we have
or
or
or
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