Q123 / 160 · TS EAMCET 2020 (11 Sep Shift 2) · Physics
Consider that a truck is moving initially with $54 \mathrm{~km} / \mathrm{h}$. It has stopped by the driver after looking at an obstacle with a deceleration of $10 \mathrm{~m} / \mathrm{s}^2$. The distance travelled by truck before coming to rest is
- A$12 \mathrm{~m}$
- Correct answerB$11.25 \mathrm{~m}$
- C$11.30 \mathrm{~m}$
- D$11.20 \mathrm{~m}$
Solution
Given, initial velocity of truck, $u=54 \mathrm{~km} / \mathrm{h}$ $=54 \times \frac{5}{18}=15 \mathrm{~m} / \mathrm{s}$
Final velocity, $v=0$
Deceleration, $a=-10 \mathrm{~m} / \mathrm{s}^2$
As we know that,
$v^2=u^2+2 a s$
$\Rightarrow \quad(0)^2=(15)^2+2 \times(-10) s \Rightarrow 20 s=(15)^2$
$s=\frac{15 \times 15}{20}=11.25 \mathrm{~m}$
Hence, the correct answer is option: 'B'.