The force required to row a boat at constant velocity is proportional ...
Given, Force(F) is directly proportional to V^2...we know, power(P)=Work/time=F S/t..As power is directly proportional to F...,then Power is proportional to V^2...P2/P1=V2^2/V1^2..P2/4=(2V)^2/(V)^2....P2=16kW...
The force required to row a boat at constant velocity is proportional ...
Problem:
The force required to row a boat at a constant velocity is proportional to the square of its speed. If a speed of v km/hr requires 4 kW, how much power does a speed of 2v km/hr require?
Solution:
Given:
- The force required to row a boat at a constant velocity is proportional to the square of its speed.
- A speed of v km/hr requires 4 kW.
To Find:
- How much power does a speed of 2v km/hr require?
Let's Solve:
Step 1: Understand the Relationship
We are given that the force required to row a boat at a constant velocity is proportional to the square of its speed. This can be represented as:
Force ∝ Speed^2
Step 2: Use the Given Information
We are also given that a speed of v km/hr requires 4 kW. This means that when the boat is moving at a speed of v km/hr, the power required is 4 kW.
Step 3: Formulate the Equation
Let's assume that the power required for a speed of 2v km/hr is P. Since force is proportional to the square of speed, we can write:
P ∝ (2v)^2
Simplifying, we get:
P ∝ 4v^2
Step 4: Use the Proportionality Constant
Since we know that a speed of v km/hr requires 4 kW, we can use this information to find the proportionality constant. Let's substitute the values into the equation:
4 kW ∝ v^2
Step 5: Solve for the Proportionality Constant
To solve for the proportionality constant, we divide both sides of the equation by v^2:
4 kW / v^2 = constant
Step 6: Find the Power for 2v km/hr
Now that we have the proportionality constant, we can find the power required for a speed of 2v km/hr. Let's substitute the values into the equation:
P ∝ 4v^2
P = constant * (2v)^2
P = constant * 4v^2
Since the proportionality constant is the same, we can substitute it with 4 kW / v^2:
P = (4 kW / v^2) * 4v^2
P = 16 kW
Answer:
A speed of 2v km/hr requires 16 kW of power. Therefore, the correct answer is B) 16kW.
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