Concept:When velocity is given as a function of position
x, acceleration is found using the chain rule:
a=vdxdv.
Explanation:The velocity of the particle is:
v=x2−5x+4To find the positions where velocity is zero, set
v=0:
x2−5x+4=0Factorising:
(x−1)(x−4)=0So the positions are:
x=1 morx=4 mNow, acceleration is the rate of change of velocity with time:
a=dtdvUsing the chain rule, since
v depends on
x and
x depends on
t:
a=dxdv⋅dtdxBut
dtdx=v, therefore:
a=vdxdvAt the points where
v=0, the product
vdxdv becomes:
a=0⋅dxdv=0Hence, the magnitude of acceleration when velocity is zero is:
0 m/s2Answer:0 m/s2Correct option: C. Zero.