Two cars start from the same place at sthe same time in the same direction.The speed of the first car is 70 km/h and that of the second car is 20m/s. (i) Which car is moving faster? (ii) What is the distance between the cars after 1 hour 15 minutes?
Answers
Answered by
1
Answer:
Suppose the second car overtakes the first car after t hours.
Then, the two cars travel the same distance in t hours.
Distance travelled by the first car in t hours =10tkm.
Distance travelled by the second car in t hours.
= Sum of t terms of an A.P. with first term 8 and common difference 1/2.
=
2
t
{2×8+(t−1)×
2
1
}=
4
t(t+31)
When the second car overtakes the first car, we have
10t=
4
t(t+31)
⟹40t=t
2
+31t⟹t
2
−9t=0
⟹t(t−9)=0⟹t=9 [∵t
=0]
Thus, the second car will overtake the first car in 9 hours.
Answered by
0
Answer:
the distance between the cars after 1 hour 15 minutes is 50km/h
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