Question

A boy takes 5 minutes to ride a cycle on a horizontal circular track of radius 2 km.
What is the distance, displacement, average speed of the boy in the following.
He reaches back to the starting point
i) As he is at the diametrically opposite point on the track.​

Answer 1

Given,

$\sf{r=2\ km=2\times 10^3\ m}$

When the boy reaches back to the starting point, distance,

$\sf{d_1=2\pi r}\\\\\\\sf{d_1=2\times 3.14\times2\times 10^3}\\\\\\\underline {\underline {\sf{d_1=1.256\times 10^4\ m}}}$

displacement,

$\underline {\underline {\sf{s_1=0\ m}}}$

Here the boy completes one cycle, then,

$\sf{t_1=5\ min=300\ s}$

Then average speed,

$\sf{v_1=\dfrac {d_1}{t_1}}\\\\\\\sf{v_1=\dfrac {1.256\times10^4}{300}}\\\\\\\underline {\underline {\sf{v_1=41.87\ ms^{-1}}}}$

When the boy is at diametrically opposite to the starting point on the track, distance,

$\sf{d_2=\pi r}\\\\\\\sf{d_2=\times 3.14\times2\times 10^3}\\\\\\\underline {\underline {\sf{d_2=6.28\times 10^3\ m}}}$

displacement,

$\sf{s_2=2r}\\\\\\\underline {\underline {\sf{s_2=4\times 10^3\ m=4\ km}}}$

Here the boy completes half cycle, then,

$\sf{t_2=2.5\ min=150\ s}$

Then average speed,

$\sf{v_2=\dfrac {d_2}{t_2}}\\\\\\\sf{v_2=\dfrac {6.28\times10^3}{150}}\\\\\\\underline {\underline {\sf{v_2=41.87\ ms^{-1}}}}$

Answer 2

Answer:

.

Explanation:

radius = 2000 m

t = 5 *60 s

= 300 s