Let’s assume the length of each train is ‘L’ and the speeds of the two trains are ‘V₁’ and ‘V₂’ respectively.
When the trains are moving in the opposite direction, their relative speed is the sum of their individual speeds. The total distance they need to cover is the sum of their lengths. Since they cross each other completely in 5 seconds, we can set up the following equation:
(V₁ + V₂) × 5 = 2L
When the trains are moving in the same direction, their relative speed is the difference between their individual speeds. The total distance they need to cover is the difference between their lengths. Since they cross each other completely in 15 seconds, we can set up the following equation:
(V₁ – V₂) × 15 = 2L
Now, let’s solve these equations to find the ratio of their speeds.
From the first equation, we have:
(V₁ + V₂) × 5 = 2L
V₁ + V₂ = (2L) / 5
From the second equation, we have:
(V₁ – V₂) × 15 = 2L
V₁ – V₂ = (2L) / 15
Let’s add these two equations together:
V₁ + V₂ + V₁ – V₂ = (2L) / 5 + (2L) / 15
2V₁ = (6L + 2L) / 15
2V₁ = (8L) / 15
V₁ = (4L) / 15
So, the speed of the first train is (4L) / 15.
Now, let’s substitute this value back into the first equation to find V₂:
(4L) / 15 + V₂ = (2L) / 5
V₂ = (2L) / 5 – (4L) / 15
V₂ = (6L – 4L) / 15
V₂ = (2L) / 15
Therefore, the speed of the second train is (2L) / 15.
The ratio of their speeds is given by:
(V₁ / V₂) = ((4L) / 15) / ((2L) / 15)
(V₁ / V₂) = 4L / 2L
(V₁ / V₂) = 2
So, the ratio of their speeds is 2:1.
A parabola is obtained as the intersection of a cone with a
plane
Ans is 2(Prime numbers)
Sum of 5 consecutive nos is 35
so X + (X+1) + (X+2) + (X+3)+ (X+4) = 35
5X + 10 = 35
X = 5
So the 5 consecutive numbers are : 5, 6, 7, 8, 9
The Prime numbers are 5 and 7
3hour 45 min = 13500 sec
In 1 sec he covers = 12 m
In 13500 sec he covers = 12×13500 m = (12×13500)/1000 km = 162 km
Ans : 162 km
mother
3 minutes
Since, there are 10 points on the circle and to draw a chord we need to connect any two points on the circle to make it a straight line, which implies that the number of chords = No of lines connecting any two points out of the 10 points
= 10C2 = 10*9/2 = 45 chords.
Let the number be 10Y+X
(10Y+X)/2 = (10X+Y)/3+6
(10Y+X)(1/2-1/3) = 6
10Y+X = 36
Therefore, sum of the digits = 3+6 = 9
Ans: 9
4/5
( b ) 40 sq cm