A) 1.5 km
B) 2 km
C) 2.5 km
D) 1.2 km
Correct Answer: A
Solution :
| [a] Given,\[u=0,\ v=90\ \operatorname{km}/h=90\times \frac{5}{18}=25m/s\] |
| From the equation of motion, |
| v = u + at |
| \[a=\frac{v}{t}\ \ \ \ \ \ \ \ \ \ [\because u=0]\] |
| \[=\frac{25}{2\times 60}\ =\frac{5}{24}\operatorname{m}/{{s}^{2}}\] |
| Distance covered is, |
| \[s=ut+\frac{1}{2}a{{t}^{2}}\] |
| \[=0+\frac{1}{2}\ \times \frac{5}{24}\times {{(120)}^{2}}\] |
| \[=\frac{1}{2}\ \times \frac{5}{24}\times 120\times 120\] |
| = 1500 m = 1.5 km |
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