Power and Machines - JSS2 Basic technology Past Questions and Answers - page 2

Power is the rate at which work is done or energy is transferred over time. It measures how quickly energy can be converted or work can be performed. The SI unit of power is the Watt (W), where one Watt equals one Joule per second. Power is crucial in understanding how efficiently machines operate, as it indicates the speed of energy conversion or work completion. Higher power means more work done in a shorter time or faster energy transfer.

Simple machines are basic mechanical devices that change the direction or magnitude of a force, such as levers, inclined planes, wheels and axles, pulleys, screws, and wedges. They have few or no moving parts and provide mechanical advantage to make tasks easier. Complex machines, or compound machines, are combinations of two or more simple machines working together. Examples include bicycles, cars, and cranes, which utilise multiple simple machines to perform more complex tasks. Complex machines are designed to handle intricate tasks efficiently by combining the benefits of simple machines.

A lever is a rigid bar that pivots around a fixed point called the fulcrum. By applying a force at one end, the lever amplifies this force to lift or move a load at the other end. The position of the fulcrum, the length of the lever arms, and the input force determine the mechanical advantage. This allows a smaller input force to move a larger load, making it easier to lift heavy objects. Levers are classified into three types based on the relative positions of the fulcrum, effort, and load.

An inclined plane is a flat surface tilted at an angle, used to raise or lower objects with less effort than lifting them vertically. It reduces the amount of force needed by increasing the distance over which the force is applied. For example, pushing a heavy box up a ramp requires less force than lifting it straight up, though the force must be applied over a longer distance. This simple machine converts a difficult lifting task into an easier pushing or pulling task. Inclined planes are commonly used in loading ramps and slides.

Pulleys are wheels with grooves that hold ropes or cables, allowing them to change the direction of an applied force. When used in a system, pulleys can also multiply the force, making it easier to lift heavy objects. For example, a single fixed pulley changes the direction of the force, while a block and tackle system (a combination of fixed and movable pulleys) can significantly reduce the effort needed to lift a load. Pulleys are used in various applications, such as lifting equipment in construction and drawing water from wells. They enhance mechanical advantage by distributing the load across multiple ropes or cables.