Question

Q30 please solve .........

Answer 1

if you differentiate x with respect to time u will get velocity and further differentiating it u will get acceleration
differentiation of 4t^2 is 8t and that of 8t is 8 therefore acceleration is 8m/s^2

Answer 2

Ans A..
Va = Ua - gt and Vb = gt are the current speeds of A and B at any time t. Ua = 10 m/s.

The relative speed is W = Va + Vb = Ua - gt + gt = Ua = 10 m/s