Question:
A car moves at a speed of 72 kmph, under a force of 600 N. The power output of the car is
A car moves at a speed of 72 kmph, under a force of 600 N. The power output of the car is
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Always ensure velocity is in ms\(^{-1}\) before calculating power in Watts. 72 kmph is a standard value used in exams and is exactly 20 ms\(^{-1}\).
Updated On: Jun 24, 2026
- 43.2 kW
- 12 kW
- 8.33 kW
- 1.2 kW
- 14.4 kW
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The Correct Option is B
Solution and Explanation
Step 1: Understanding the Concept:
Power is the rate at which work is done. For an object moving with a constant velocity under a constant force, power is the dot product of force and velocity.
Step 2: Key Formula or Approach:
1. Power \(P = F \times v\).
2. Convert kmph to ms\(^{-1}\) using the factor \(\frac{5}{18}\).
Step 3: Detailed Explanation:
Step 1: Convert speed to standard SI units.
\[ v = 72 \times \frac{5}{18} = 20 \text{ ms}^{-1} \]
Step 2: Calculate Power using the given force.
\[ P = F \times v = 600 \text{ N} \times 20 \text{ ms}^{-1} \]
\[ P = 12000 \text{ Watts} \]
Step 3: Convert to kilowatts.
\[ P = \frac{12000}{1000} = 12 \text{ kW} \]
Step 4: Final Answer:
The power output of the car is 12 kW.
Power is the rate at which work is done. For an object moving with a constant velocity under a constant force, power is the dot product of force and velocity.
Step 2: Key Formula or Approach:
1. Power \(P = F \times v\).
2. Convert kmph to ms\(^{-1}\) using the factor \(\frac{5}{18}\).
Step 3: Detailed Explanation:
Step 1: Convert speed to standard SI units.
\[ v = 72 \times \frac{5}{18} = 20 \text{ ms}^{-1} \]
Step 2: Calculate Power using the given force.
\[ P = F \times v = 600 \text{ N} \times 20 \text{ ms}^{-1} \]
\[ P = 12000 \text{ Watts} \]
Step 3: Convert to kilowatts.
\[ P = \frac{12000}{1000} = 12 \text{ kW} \]
Step 4: Final Answer:
The power output of the car is 12 kW.
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