A man uses a crowbar of length 1.5m to raise a load of 75 kgf by putting a sharp edge below the bar at a distance of 1 m from his hand. (a) draw a diagram of the arrangement showing the fulcrum (F), load (L) and effort (E) with their direction. (b) state the kind of lever. (c) Calculate : (i) load arm, (ii) effort arm, (iii) mechanical advantage, and (iv) the effort needed.

Answer

### Step-by-Step Solution

**(a) Diagram of the Arrangement:**
1. Draw a horizontal line representing the crowbar.
2. Mark the fulcrum (F) at a point on the line, which is the point where the crowbar pivots.
3. On one side of the fulcrum, mark the load (L) at a distance of 0.5 m from the fulcrum (since the total length of the crowbar is 1.5 m and the effort arm is 1 m).
4. On the other side of the fulcrum, mark the effort (E) at a distance of 1 m from the fulcrum, indicating the direction of the effort as downward.
5. Label the directions of the load (downward) and the effort (downward) in the diagram.

**(b) Kind of Lever:**
- Since the fulcrum (F) is located between the load (L) and the effort (E), this arrangement is classified as a **Class 1 lever**.

**(c) Calculations:**
1. **Load Arm (LA):**
- The load arm is the distance from the fulcrum to the load.
- Given that the total length of the crowbar is 1.5 m and the effort arm is 1 m:
\[ \text{Load Arm} = \text{Total Length} - \text{Effort Arm} = 1.5 \, \text{m} - 1 \, \text{m} = 0.5 \, \text{m} \]

2. **Effort Arm (EA):**
- The effort arm is given as 1 m.

3. **Mechanical Advantage (MA):**
- The mechanical advantage is calculated using the formula:
\[ \text{Mechanical Advantage} = \frac{\text{Effort Arm}}{\text{Load Arm}} = \frac{1 \, \text{m}}{0.5 \, \text{m}} = 2 \]

4. **Effort Needed (E):**
- The effort needed can be calculated using the formula:
\[ \text{Effort} = \frac{\text{Load}}{\text{Mechanical Advantage}} = \frac{75 \, \text{kgf}}{2} = 37.5 \, \text{kgf} \]

### Summary of Results:
- Load Arm (LA) = 0.5 m
- Effort Arm (EA) = 1 m
- Mechanical Advantage (MA) = 2
- Effort Needed = 37.5 kgf