Question

The position of an object moving along x-axis is given by x = a + $b{t}^2$, where a = 8.5 m and b = 2.5 m $s^{-2}$ and t is measured in seconds. The instantaneous velocity of the object at t = 2 s is

• A. 5 m $s^{-1}$
• B. 10 m $s^{-1}$
• C. 15 m $s^{-1}$
• D. 20 m $s^{-1}$

Answer 1

Answer: (B)

10 m $s^{-1}$

Given:

$a=8.5b=2.5$

$x=a+b{t}^2$

$\frac{dx}{dt}=2bt$

$V_{t=2}=\frac{dx}{dt}=2\times 2.5\times 2=10m{s}^{-1}$