Question

The displacement (x) variation of a particle with time (t) is given by expression $x=-15t^2+20t+30$ . What is the velocity at $t=0$ ?

• A. 30
• B. 20
• C. -30
• D. -20

Answer 1

Answer: (B)

20

$v\left(t\right)=dx\left(t\right)/dt=-30t+20$

$v\left(0\right)=20$

Therefore, the velocity at $t=0$ is $20m/s$.