Name a machine which is used to :
(a) multiply force,
(ii) multiply speed, and
(c) change the direction of force applied.

Answer

To answer the question, we need to identify machines that serve three specific functions: multiplying force, multiplying speed, and changing the direction of force applied. Let's break it down step by step.

### Step-by-Step Solution:

1. **Multiplying Force:**
- The machine that is commonly used to multiply force is a **movable pulley**.
- In a movable pulley system, the load is attached to the pulley itself, allowing the effort (force) applied to lift the load to be less than the weight of the load. This is because the tension in the rope is distributed across multiple segments, effectively multiplying the force exerted.

2. **Multiplying Speed:**
- To multiply speed, we use a **Class 3 lever**.
- In a Class 3 lever, the effort is applied between the fulcrum and the load. This arrangement allows the load to move a greater distance than the effort, thus increasing speed. For instance, when you lift a load with a Class 3 lever, the load moves faster than the effort applied.

3. **Changing the Direction of Force Applied:**
- A **fixed pulley** is used to change the direction of the force applied.
- In a fixed pulley system, the pulley is anchored in place, and when you pull down on the rope, the load is lifted upwards. This allows the user to apply force in a more convenient direction, effectively changing the direction of the applied force.

### Final Answers:
- (a) Multiply force: **Movable Pulley**
- (b) Multiply speed: **Class 3 Lever**
- (c) Change the direction of force applied: **Fixed Pulley**