Physical Science Chapter 5 - 3

Explanation
A wheel and axle is another modified lever. The center of the axle is the fulcrum. The input force is applied at the rim of the wheel. So the length of the input arm is the radius of the wheel.

Explanation
Gears are the correct answer because they are a mechanism that consists of toothed wheels connected by an axle. The teeth on the wheels of the gears allow for the transfer of motion and force from one wheel to another, making them useful in various applications such as machinery and vehicles.

Explanation
The correct answer is "ramp" because a ramp is an inclined plane that allows for easier movement of objects from a lower to a higher level. A ramp is commonly used to assist in the movement of heavy objects, such as loading and unloading trucks or wheelchairs accessing buildings. It provides a gradual slope, eliminating the need for lifting or using excessive force. Therefore, a ramp is the most suitable option among the given choices.

Explanation
The correct answer is "screws" because an inclined plane wrapped in a spiral around a cylindrical post is the basic design of a screw. Screws are simple machines that convert rotational motion into linear motion, allowing them to be used for various purposes such as fastening objects together or lifting heavy loads. The spiral shape of the inclined plane, which is wrapped around the cylindrical post, creates a helical structure that enables the screw to move through a material or engage with another object when rotated.

Explanation
A knife and a wedge are both examples of simple machines that use inclined planes to perform work. When a knife is used to cut through an object, the sharp edge of the blade acts as an inclined plane, reducing the force required to separate the material. Similarly, a wedge is a type of inclined plane with a thick end and a sharp edge, which allows it to split objects apart by applying a smaller force over a larger distance. Therefore, both a knife and a wedge can move through an object or material using the principle of inclined planes.

Explanation
Compound machines are made up of two or more simple machines that work together to perform a task. They combine the advantages of different simple machines to make work easier. In this case, the answer "compound machines" is the correct one as it accurately describes the concept of multiple simple machines working together.