A coolie 1.5 m tall raises a load of 80 kg in 2 sec from the ground to his head and then walks a distance of 40 m in another 2 second. The power developed by the coolie is : `(g = 10 m//s^(2))`

Options

A. 0.2 kW
B. 0.4 kW
C. 0.6 kW
D. 0.8 kW

Answer

To find the power developed by the coolie, we need to calculate the work done in lifting the load and then determine the power based on the time taken.

### Step 1: Calculate the Work Done in Lifting the Load
The work done (W) in lifting an object is given by the formula:

\[ W = m \cdot g \cdot h \]

where:
- \( m \) = mass of the load (80 kg)
- \( g \) = acceleration due to gravity (10 m/s²)
- \( h \) = height to which the load is lifted (1.5 m)

Substituting the values:

\[ W = 80 \, \text{kg} \cdot 10 \, \text{m/s}^2 \cdot 1.5 \, \text{m} \]

Calculating this:

\[ W = 80 \cdot 10 \cdot 1.5 = 1200 \, \text{J} \]

### Step 2: Calculate the Power Developed
Power (P) is defined as the work done per unit time. The formula for power is:

\[ P = \frac{W}{t} \]

where:
- \( W \) = work done (1200 J)
- \( t \) = time taken to lift the load (2 seconds)

Substituting the values:

\[ P = \frac{1200 \, \text{J}}{2 \, \text{s}} \]

Calculating this:

\[ P = 600 \, \text{W} \]

### Step 3: Convert Power to Kilowatts
To convert watts to kilowatts, we divide by 1000:

\[ P = \frac{600 \, \text{W}}{1000} = 0.6 \, \text{kW} \]

### Final Answer
The power developed by the coolie is **600 W** or **0.6 kW**.

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