Question

300 J of work is done in sliding a 2 kg block up an inclined plane of height 10 m. Taking g =10 m/s², work done against friction is :

• A. 50 J
• B. 100 J
• C. zero
• D. 150 J

Answer 1

The Correct Option is B

To determine the work done against friction when sliding a 2 kg block up an inclined plane of height 10 m, we start by analyzing the given information and applying relevant physics concepts.

The fundamental idea here is to account for the total work done, which includes both the work done against gravity and the work done against friction.

1. Calculate the Work Done Against Gravity:

   The work done against gravity when moving an object to a certain height is given by the formula:

   W_{\text{gravity}} = m \cdot g \cdot h

   Here, m = 2 \, \text{kg}, g = 10 \, \text{m/s}^2, and h = 10 \, \text{m}.

   Substitute these values into the formula:

   W_{\text{gravity}} = 2 \cdot 10 \cdot 10 = 200 \, \text{J}

2. Determine the Total Work Done:

   It is given that the total work done in sliding the block is 300 J.

3. Calculate the Work Done Against Friction:

   The work done against friction can be found by subtracting the work done against gravity from the total work done:

   W_{\text{friction}} = W_{\text{total}} - W_{\text{gravity}}

   Substituting the known values, we get:

   W_{\text{friction}} = 300 - 200 = 100 \, \text{J}

Therefore, the work done against friction is 100 J, which confirms that the correct answer is 100 J.