A block of mass 50 kg slides over a horizontal distance of 1m. If the coefficient of friction between their surface is 0.2, then work done against friction is (take `g = 9.8 m//s^(2)`) :

Options

A. 98 J
B. 72 J
C. 56 J
D. 34 J

Explanation

To solve the problem of calculating the work done against friction when a block of mass 50 kg slides over a horizontal distance of 1 meter with a coefficient of friction of 0.2, we can follow these steps:

### Step 1: Identify the given values
- Mass of the block (m) = 50 kg
- Distance slid (d) = 1 m
- Coefficient of friction (μ) = 0.2
- Acceleration due to gravity (g) = 9.8 m/s²

### Step 2: Calculate the normal force (N)
The normal force for an object resting on a horizontal surface is equal to the weight of the object. The weight can be calculated using the formula:
\[ N = m \cdot g \]
Substituting the values:
\[ N = 50 \, \text{kg} \cdot 9.8 \, \text{m/s}^2 = 490 \, \text{N} \]

### Step 3: Calculate the frictional force (F_friction)
The frictional force can be calculated using the formula:
\[ F_{\text{friction}} = \mu \cdot N \]
Substituting the values:
\[ F_{\text{friction}} = 0.2 \cdot 490 \, \text{N} = 98 \, \text{N} \]

### Step 4: Calculate the work done against friction (W)
The work done against friction can be calculated using the formula:
\[ W = F_{\text{friction}} \cdot d \]
Substituting the values:
\[ W = 98 \, \text{N} \cdot 1 \, \text{m} = 98 \, \text{J} \]

### Final Answer
The work done against friction is **98 Joules**.

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