Q1: What is a machine?

Answer: A machine is a device that makes work easier or faster by changing the direction or magnitude of a force.

Q2: What is a simple machine?

Answer: A simple machine is a basic mechanical device that changes the direction or magnitude of a force, requiring only one applied force to do work.

Q3: Name the six types of simple machines.

Answer: The six types of simple machines are: lever, pulley, wheel and axle, inclined plane, wedge, and screw.

Q4: What is a lever? Name its three classes.

Answer: A lever is a rigid bar that pivots around a fixed point called the fulcrum. Its three classes are:

• First-class lever: Fulcrum is between effort and load (e.g., seesaw, crowbar).
• Second-class lever: Load is between fulcrum and effort (e.g., wheelbarrow, nutcracker).
• Third-class lever: Effort is between fulcrum and load (e.g., fishing rod, tweezers).

Q5: What is a pulley? Give an example of its use.

Answer: A pulley is a wheel with a grooved rim over which a rope or cable passes. It is used to lift heavy objects or change the direction of force. Example: Lifting a bucket from a well, flagpoles.

Q6: What is a wheel and axle? Give an example.

Answer: A wheel and axle is a simple machine consisting of a wheel attached to a smaller rod (axle) so that they rotate together. It is used to move objects or apply force. Example: Steering wheel, doorknob, bicycle wheel.

Q7: What is an inclined plane? Give an example.

Answer: An inclined plane is a flat, sloping surface that connects a lower level to a higher level. It is used to move objects up or down with less force. Example: A ramp, a slide, a sloping road.

Q8: What is a wedge? Give an example.

Answer: A wedge is a simple machine that consists of two inclined planes joined together, tapering to a sharp edge. It is used to split, cut, or separate objects. Example: Axe, knife, chisel, doorstop.

Q9: What is a screw? Give an example.

Answer: A screw is a simple machine that is an inclined plane wrapped around a cylinder. It is used to hold things together, lift objects, or move things. Example: Wood screw, bottle cap, drill bit, jack screw.

Q10: How do simple machines make work easier?

Answer: Simple machines make work easier by reducing the amount of force needed, changing the direction of the force, or increasing the distance over which the force is applied.

Q11: What is the fulcrum in a lever?

Answer: The fulcrum is the fixed pivot point around which a lever rotates.

Q12: What is the effort in a machine?

Answer: The effort is the force applied to the machine to do work.

Q13: What is the load (or resistance) in a machine?

Answer: The load (or resistance) is the force that the machine works against, or the object being moved.

Q14: Give an example of a first-class lever from daily life.

Answer: A seesaw is a first-class lever where the fulcrum is in the middle, between the effort and the load.

Q15: Give an example of a second-class lever from daily life.

Answer: A wheelbarrow is a second-class lever where the load (contents of the wheelbarrow) is between the fulcrum (the wheel) and the effort (where you lift the handles).

Q16: Give an example of a third-class lever from daily life.

Answer: A fishing rod is a third-class lever where the effort (your hand pulling the rod) is between the fulcrum (where the rod rests) and the load (the fish at the end).

Q17: How does an inclined plane reduce the force needed to lift an object?

Answer: An inclined plane reduces the force needed to lift an object by spreading the work over a longer distance. Instead of lifting straight up, you push it along a slope, requiring less effort at any given moment.

Q18: What is a compound machine? Give an example.

Answer: A compound machine is a machine made up of two or more simple machines working together. Example: A bicycle (uses wheels and axles, levers, and screws), a pair of scissors (uses two levers and two wedges).

Q19: What is the mechanical advantage of a machine?

Answer: Mechanical advantage is the ratio of the output force (load) to the input force (effort), indicating how much a machine multiplies the force applied.

Q20: How does a screw hold things together?

Answer: A screw holds things together by converting rotational motion into linear motion. As it turns, its threads bite into the material, creating a strong grip.

Q21: What is the benefit of using a pulley system with multiple pulleys?

Answer: A pulley system with multiple pulleys (block and tackle) increases the mechanical advantage, allowing a much heavier load to be lifted with less effort, though the rope needs to be pulled a longer distance.

Q22: How does a wedge help in cutting objects?

Answer: A wedge helps in cutting objects by concentrating the applied force onto a small, sharp edge, which then pushes the material apart as it moves through it.

Q23: Give an example of a simple machine used in a playground.

Answer: A seesaw (lever), a slide (inclined plane), or a merry-go-round (wheel and axle) are examples of simple machines found in a playground.

Q24: Why is a doorknob considered a wheel and axle?

Answer: A doorknob is considered a wheel and axle because the larger knob (wheel) rotates a smaller shaft (axle) inside, allowing us to easily turn the latch and open the door with less effort.

Q25: What is the importance of simple machines in human history?

Answer: Simple machines have been fundamental throughout human history, enabling early civilizations to build structures, move heavy objects, and develop tools that greatly advanced technology and daily life.

Q26: How does a ramp make it easier to load heavy objects into a truck?

Answer: A ramp (inclined plane) makes it easier to load heavy objects into a truck by allowing you to push the object over a longer distance with less force, rather than lifting it directly upwards against gravity.

Q27: What is the relationship between force, distance, and work in simple machines?

Answer: Simple machines demonstrate that while they may reduce the force needed, they often require that force to be applied over a greater distance, keeping the total work done (force x distance) constant (ignoring friction).