A) 1 hr
B) 1/2 hr
C) 1/4 hr
D) 1/8 hr
Correct Answer: B
Solution :
Let car B catches car A after ?t? sec, then \[60t+2.5=70t-\frac{1}{2}\times 20\times {{t}^{2}}\] \[\Rightarrow \,\,\,10{{t}^{2}}-10t+2.5=0\,\,\Rightarrow \,\,{{r}^{2}}-t+0.25=0\] \[\therefore \,\,\,\,t=\frac{1\pm \sqrt{1-4\times (0.25)}}{2}\,\,=\,\,\frac{1}{2}\,h\]You need to login to perform this action.
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