Question

The displacement is given by $x=2t^2+t+5$ in $\text{m}$, the acceleration at $t=5s$ will be

• A. $8{\text{m/s}}^2$
• B. $12{\text{m/s}}^2$
• C. $15{\text{m/s}}^2$
• D. $4{\text{m/s}}^2$

Answer 1

The correct option is D $4{\text{m/s}}^2$

As we know that $a=\frac{d^{2}x}{d{t}^2}$
Given, $x=2t^2+t+5\Rightarrow \frac{dx}{dt}=4t+1\Rightarrow \frac{d^{2}x}{d{t}^2}=4$
$\Rightarrow a={\left(\frac{d^{2}x}{d{t}^2}\right)}_{t=5\text{s}}=4{\text{m/s}}^2$