Long Answers

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Last edited 26 days ago by Learn LoopHQ.

Chapter: 05. Simple Machine

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How do machines make our daily lives easier and safer, according to the advantages discussed?

Machines significantly ease our daily tasks by reducing the effort needed, such as using a screw jack to lift a car. They also accelerate work, allowing tasks like trimming plants to be completed much faster. Furthermore, machines can change the direction of force, making actions like drawing water from a well more convenient. They allow force to be applied at a practical point for an effect elsewhere, like a hammer driving a nail. Crucially, machines enable us to perform dangerous or unsafe jobs from a distance, enhancing safety.

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Explain the key terms associated with simple machines: Load, Effort, Fulcrum, Load Arm, and Effort Arm.

Load is the weight or resistance that the machine is designed to lift or overcome. Effort is the external force that is applied to the machine to make it work and move the load. The Fulcrum is the fixed pivot point around which the machine turns or rotates. The Load Arm is the shortest distance measured from where the load is acting to the fulcrum. Finally, the Effort Arm is the shortest distance from where the effort is applied to the fulcrum.

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Describe the Law of Levers and explain how it relates to the mechanical advantage of a lever.

The Law of Levers states that for a lever to be balanced, the product of the load and its distance from the fulcrum (load arm) must be equal to the product of the effort and its distance from the fulcrum (effort arm). This relationship is expressed as Load × Load arm = Effort × Effort arm. Mechanical advantage (MA), defined as Load/Effort, can also be derived from this law. By rearranging the law of levers, we find that MA is also equal to the ratio of the effort arm to the load arm (Effort arm / Load arm). This means a longer effort arm relative to the load arm increases the mechanical advantage, making it easier to lift heavier loads.

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Differentiate between the three orders of levers, providing an example for each.

Levers are classified by the relative positions of the fulcrum (F), load (L), and effort (E). In a first-order lever, the fulcrum is located between the load and the effort (L-F-E), like a seesaw. Its mechanical advantage can be greater than, less than, or equal to one. A second-order lever has the load positioned between the fulcrum and the effort (F-L-E), such as a nutcracker; these always have a mechanical advantage greater than one, acting as force multipliers. A third-order lever places the effort between the fulcrum and the load (F-E-L), for instance, a human arm lifting a weight; these always have a mechanical advantage less than one and are often used for speed or range of motion.

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Define an inclined plane and explain how its mechanical advantage is determined. Provide an example.

An inclined plane is a simple machine consisting of a flat surface tilted or sloped to the horizontal. Its purpose is to allow heavy loads to be moved easily by sliding or rolling them along the slope, rather than lifting them vertically. The mechanical advantage of an inclined plane is determined by the ratio of the distance the load travels along the inclined surface to the vertical height the load is lifted. For example, a longer, less steep ramp (greater distance traveled for the same height) will have a higher mechanical advantage, requiring less effort.

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Describe a screw and list some of its important uses in daily life.

A screw is a simple machine that is essentially an inclined plane wrapped around a cylinder, appearing as a nail with a spiral groove called threads. It has a pointed tip and a flat head with a slit for turning. Screws are primarily used to fasten two pieces of wood or metal together securely, as their threads grip firmly into the material. Other common uses include corkscrews for opening bottles, nuts and bolts for holding components together under pressure, and screw jacks for lifting heavy objects like cars during tire changes. Drills also utilize a screw-like mechanism to create holes.

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Explain the concept of a wheel and axle and provide examples of its use.

A wheel and axle is a simple machine arrangement where a larger wheel is rigidly attached to a smaller central rod, or axle. When effort is applied to turn either the wheel or the axle, the other also rotates. This setup allows a smaller effort applied to the wheel to move a much larger load connected to the axle, providing mechanical advantage. Common examples include a doorknob, where turning the knob (wheel) rotates the central spindle (axle) to operate the latch, or the steering wheel of a car, which turns a shaft to control the wheels. Taps and screwdrivers also function on the principle of a wheel and axle.

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Differentiate between a single fixed pulley and a single movable pulley, explaining their main functions.

A single fixed pulley consists of a pulley attached to a stationary support, meaning the pulley itself does not move. Its primary function is to change the direction of the effort, making it more convenient to lift a load; for instance, pulling downwards on a rope to lift a bucket from a well. In contrast, a single movable pulley is not attached to a fixed support but moves with the load. Its main function is to multiply force: since the load is supported by two segments of the rope, the effort required to lift the load is halved. However, it typically requires pulling the rope upwards, which can be less convenient.

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Define the efficiency of a machine and explain why a practical machine’s efficiency is always less than 100%.

The efficiency of a machine is defined as the ratio of its useful output energy (work done by the machine) to the total input energy (work done on the machine). It is often expressed as a percentage. In a practical machine, the efficiency is always less than 100% because some of the input energy is invariably converted into unusable forms, primarily heat and sound, due to friction between the machine’s moving parts. This energy loss means that the output energy can never be equal to or greater than the input energy, preventing 100% efficiency.

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What are compound machines, and how do their mechanical advantage and efficiency compare to simple machines?

Compound machines are devices made up of two or more simple machines working together to perform a more complex task. They tend to have a greater overall mechanical advantage compared to single simple machines because the mechanical advantages of their component simple machines are multiplied. However, their efficiency is generally lower than that of simple machines. This reduced efficiency occurs because the presence of multiple moving parts increases the total friction within the system, leading to greater energy loss.

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List and explain four essential steps for the proper maintenance and care of machines.

Proper maintenance ensures machines work well and last longer. First, regular cleaning is crucial to prevent dust and grime from accumulating and interfering with moving parts. Second, lubrication of moving parts with oil is essential to reduce friction, minimize noise, and prevent excessive wear and tear. Third, painting the iron parts of machines helps prevent rust, which can corrode components and impair function. Finally, covering machines when not in use protects them from dust and moisture, maintaining their condition for future operation.

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