Science -term-1-work And Energy

Explanation
A pulley is a machine made up of a wheel and rope. It is used to lift or move heavy objects by changing the direction of the force applied. The wheel, known as the pulley, has a groove along its circumference where the rope or cable is placed. When force is applied to one end of the rope, it causes the wheel to rotate, allowing for the movement of the load. The pulley system provides mechanical advantage, making it easier to lift heavy objects.

Explanation
Energy is defined as the ability to do work. It is a fundamental concept in physics and is measured in various units such as joules or calories. Energy can exist in different forms such as kinetic energy, potential energy, thermal energy, and chemical energy. It is the capacity of a system to perform work or produce heat. In the context of this question, energy is the correct answer as it directly relates to the ability to do work.

Explanation
A lever is classified into three types: first-class lever, second-class lever, and third-class lever. These classifications are based on the relative positions of the fulcrum, the effort force, and the load. Each type of lever has different characteristics and is used in different ways. Therefore, the correct answer is 3.

Explanation
The SI unit of energy is joule. The joule is a derived unit of energy in the International System of Units (SI). It is defined as the amount of work done when a force of one newton is applied over a distance of one meter. The joule is commonly used to measure various forms of energy such as mechanical, electrical, and thermal energy.

Explanation
The blade and sharpener are held together by a screw. A screw is a threaded fastener that is used to hold objects together by applying rotational force. In this case, the screw is used to secure the blade and sharpener tightly, ensuring that they remain in place and function properly.

Explanation
An inclined plane is a simple machine that consists of a sloping surface. It is used to reduce the effort required to move an object vertically by increasing the distance over which the force is applied. A ramp is a common example of an inclined plane as it allows objects to be moved up or down with less force compared to lifting them straight up. It provides a gradual slope, making it easier to transport heavy objects such as furniture or vehicles.

Explanation
Simple machines are designed to make work easier by reducing the amount of force required to perform a task. They achieve this by either increasing the distance over which the force is applied or by changing the direction of the force. Examples of simple machines include levers, pulleys, inclined planes, and wheels and axles. Therefore, the statement "simple machines help us to make work easier" is true.

Explanation
The statement that "Nail cutter belongs to class II lever" is false. A class II lever is a lever where the load is between the fulcrum and the effort. In the case of a nail cutter, the fulcrum is located at the pivot point, but the effort (the force applied by the user) is also located at the same end. The load (the nail being cut) is located at the opposite end. Therefore, a nail cutter belongs to class III lever, where the effort is between the fulcrum and the load.

Explanation
The statement is true because a wedge is a simple machine that is used to split or separate objects. A knife, scissors, and an axe are all examples of wedges because they have a sharp edge that is used to exert pressure and separate materials.

Explanation
The force we apply on the lever is known as the effort.