All questions of Machines for Grade 9 Exam

Understanding Inclined Planes
An inclined plane is a flat surface that is tilted at an angle to help lift or lower objects. It reduces the amount of force needed to move something upward, making it easier to transport heavy objects.
Example: The Ramp
Among the options provided, a ramp is the best example of an inclined plane in everyday life. Here’s why:
Characteristics of a Ramp:
- Sloped Surface: A ramp is typically a sloped surface that connects two different heights. This slope makes it easier to move items from a lower level to a higher one.
- Force Reduction: Instead of lifting a heavy object directly, a ramp allows you to roll or slide it up. The incline reduces the effort required to lift the object.
- Common Uses: Ramps are widely used in various settings, such as:
- Loading Docks: To load goods onto trucks.
- Wheelchair Accessibility: To provide access to buildings for individuals with mobility challenges.
- Stadiums and Theaters: For easy movement between different seating levels.
Comparison with Other Options:
- Screw: A screw is a type of fastener and operates based on the principle of a helix, not an inclined plane.
- Hammer: A hammer is a tool used for driving nails and does not feature an inclined surface.
- Pulley: A pulley is a mechanism that helps lift objects using a rope and wheel system, not an inclined plane.
In conclusion, a ramp effectively exemplifies an inclined plane, as it simplifies lifting tasks by utilizing a sloped surface.

Understanding Pulleys
Pulleys are simple machines that help lift heavy loads with less effort. They come in two main types: fixed pulleys and movable pulleys. Let's explore the differences between them.
Movable Pulley
- A movable pulley is attached to the load itself, meaning it moves along with the object being lifted.
- This design allows for a reduction in the amount of force needed to lift the load, making it easier to move heavier items.
- Since the pulley moves with the load, it provides a mechanical advantage, allowing the user to lift more weight with less effort.
Fixed Pulley
- A fixed pulley, on the other hand, is anchored in one place and does not move with the load.
- It primarily changes the direction of the force applied. For example, if you pull down on a rope, the load goes up.
- While it can make lifting easier by allowing for direction change, it does not reduce the amount of force required to lift the load.
Key Differences
- Movement: The movable pulley moves with the load, while the fixed pulley remains stationary.
- Force: The movable pulley provides a mechanical advantage, making it easier to lift heavier loads compared to the fixed pulley.
- Applications: Fixed pulleys are often used in scenarios where direction change is needed, while movable pulleys are ideal for lifting heavier items in various settings, including construction.
In summary, option 'A' is correct because a movable pulley indeed moves with the load, offering significant advantages in lifting efficiency.