Duration of a metro journey varies directly as the distance and invers...
Where t is time, s is distance, v is velocity, Q is the amount of electricity used, n is the number of carriages and k1,k2 k care constants. Also, k = k1,k2
Hence, option 4.
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Duration of a metro journey varies directly as the distance and invers...
To solve this problem, we can break it down into smaller steps. Let's start by identifying the given information and the variables involved:
Given:
- Duration of the metro journey varies directly with the distance and inversely with the velocity.
- Velocity varies directly with the square root of the quantity of electricity used and inversely with the number of carriages in the train.
- A journey of 50 km in half an hour with 18 carriages requires 100 units of electricity.
Variables:
- Distance: d (in km)
- Duration: t (in minutes)
- Velocity: v (in units)
- Electricity used: e (in units)
- Number of carriages: c
Step 1: Determine the relationship between duration, distance, and velocity
Since the duration varies directly with the distance and inversely with the velocity, we can write the equation as:
t ∝ d/v
Step 2: Determine the relationship between velocity, electricity used, and number of carriages
Since the velocity varies directly with the square root of the electricity used and inversely with the number of carriages, we can write the equation as:
v ∝ √e/c
Step 3: Combine the two equations to solve for the variables
Substituting the equation from Step 2 into the equation from Step 1, we get:
t ∝ d/(√e/c)
Simplifying the equation, we get:
t ∝ d√(c/e)
Step 4: Use the given information to find the proportionality constant
We can use the given information about the journey of 50 km in half an hour with 18 carriages requiring 100 units of electricity to find the proportionality constant.
Using the formula t ∝ d√(c/e), we have:
0.5 ∝ 50√(18/100)
Simplifying the equation, we get:
0.5 ∝ 50√(9/50)
0.5 ∝ 50(3/5)
0.5 ∝ 30
Therefore, the proportionality constant is 30.
Step 5: Use the proportionality constant to solve for the electricity used in the new journey
Now that we have the proportionality constant, we can use it to find the electricity used in the journey of 42 km in 28 minutes with 16 carriages.
Using the formula t ∝ d√(c/e), we have:
28 ∝ 42√(16/e)
Simplifying the equation, we get:
28 ∝ 42√(4/e)
28 ∝ 84/√e
Using the proportionality constant of 30, we can write the equation as:
28 = 30(84/√e)
Simplifying the equation, we get:
28 = 2520/√e
Cross-multiplying and squaring both sides of the equation, we get:
784 = 2520/e
Simplifying the equation, we get:
e = 2520/784
e ≈ 3.214
Therefore, the electricity consumed in the journey of 42 km in 28 minutes with 16 carriages is approximately 3.214 units.
The correct answer is not provided in the options given.
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