Question

37
A
30. A car moves a distance of 100 m. It coveres first
half with speed of 10 m/s and another half with
speed of v m/s. If the average speed of car is
18 m/s, then value of v is
(1) 60 m/s
(2) 80 m/s
(3) 90 m/s
(4) 110 m/s

Answer 1

Average Speed =Total Speed/Total time


S1=10m/s
S2=x m/s


Average Speed=18m/s
Distance(Total)=100m


Now putting all values in formula we get;

10×x/100=18
X=1800
x=180m

Answer 2

Answer:

90 m/s

Explanation:

Av. speed =total distance/total time

first half distance is =50

so time taken to cover half distance is 50/10=5 sec.

time taken to cover second half distance is 50/v so av. speed= 100/5+50/v=18

then v= 90m/s