UPSEE Solved Model Paper 7

Given:
Distance, s = t3 + 5
At any instant t, velocity is
v =

ds

dt

= 3t2
At time t = 2 s
⇒ v = 3×22 = 12 m/s
Than , the centripetal acceleration that is produced radially and directed towards the centre is
ac =

v2

r

=

122

20

= 7.2 m∕s2
Tangential acceleration is
aT =

dv

dt

= 5t
At time t = 2 s, magnitude of the tangential acceleration is given by
aT = 6 × 2 = 12m∕s2
The magnitude of the resultant acceleration is
a = √ac2+aT2
⇒ a = √(7.2m∕s2)2+(12m∕s2)2
⇒ a = 14m∕s2
Hence, option 'A' is correct.