A particle moves along a straight line OX. At a time t (in second) the distance x ( in metre ) of the particle from O is given by x = 40 + 12 t - t3 . How long would the particle travel before coming to rest?
24 m
40 m
56 m
16 m
C.
56 m
Speed is rate of change of distance.
Distance travelled by the particle is
x = 40 + 12 t - t3
We know the speed is rate of change of distance
i.e
= 0 + 12 - 3t2
but final velocity ν = 0
∴ 12 - 3t2 = 0
⇒
⇒ t = 2s
Hence, distance travelled by the particle before coming to rest is given by
x = 40 + 12(2)-(2)3
x = 64 - 8
x = 56 m