Q.

A particle starts moving from time t=0 and its coordinate is given as x(t)=4t3−3t.           [2026]

A. The particle returns to its original position (origin) 0.866 units later.

B. The particle is 1 unit away from origin at its turning point.

C. Acceleration of the particle is non-negative.

D. The particle is 0.5 units away from origin at its turning point.

E. Particle never turns back as acceleration is non-negative.

Choose the correct answer from the options given below:

1 A, C, D only  
2 A, B, C only  
3 C, E only  
4 A, C only  

Ans.

(2)

x(t)=4t3-3t

For  x(t)=0⇒t(4t2-3)=0

⇒t=32≈0.866 units

v(t)=12t2-3

Turning point at v=0

t2=14⇒t=0.5 units

At t=12 unit,  x(12)=4(12)3-3(12)=-1.0 unit

a(t)=24t

which is non-negative for t≥0.