if a boy runs along a circular field of 200m diameter in 40 seconds. How much distance will he cover in 2 minutes and 20 seconds and what shall be his displacement
s =π•D,
v=s/t = π•D/t = 200• π/40 =5•π m/s =15.7m/s.
s1 = v•t1 =5•π•140 = 700•π =2199 m.
During 3 min it was made 700•π/200•π = 3.5 rev, therefore, the displacement is 2R = D.
But… I believe that there is a mistake in your given data: according to them this boy has to cover 100 m for 100/15.7 =6.37 s. WR Usain Bolt of is 9,58 s.