J7 Simple machines Post test

A machine is best described as a device that:

• performs tasks without human assistance.

• makes a physical task easier.

• uses electricity to do work.

• is controlled by a computer.

Answer explanation

A machine is primarily designed to make physical tasks easier, enhancing efficiency and reducing effort. While it may perform tasks without human assistance or use electricity, its core function is to simplify tasks.

The turning point of a lever is:

• its centre.

• the load.

• the fulcrum.

• the base.

Answer explanation

The turning point of a lever is called the fulcrum. It is the fixed point around which the lever pivots, allowing it to lift or move a load effectively.

The resistance to motion that a lever works against is called the:

• effort.

• load.

• force.

• fulcrum.

Answer explanation

The resistance to motion that a lever works against is known as the load. It represents the weight or force that the lever must overcome to perform work, making 'load' the correct choice.

When you bend your arm to lift an object like a bucket, the fulcrum is your:

• biceps.

• triceps.

• forearm.

• elbow.

Answer explanation

The elbow acts as the fulcrum when you bend your arm to lift an object. The biceps and triceps are muscles that help in the movement, but the pivot point for the lever system is the elbow joint.

If the effort moves the end of the lever down 1 metre, how high will it lift the load?

• 3 metres

• 4 metres

• 1 metre

• 1/3 metre

Answer explanation

Using the principle of levers, if the effort moves down 1 metre, the load will lift up by a ratio determined by the lever's lengths. Here, it lifts the load by 1/3 metre, making the correct answer 1/3 metre.

A ramp is:

• a machine.

• not a machine, but is used by machines.

• a fourth-order lever.

• a device involving rollers used to move heavy objects.

Answer explanation

A ramp is classified as a machine because it helps to lift heavy objects by converting vertical movement into horizontal movement, making work easier. This aligns with the definition of a simple machine.

The centre of a wheel and axle is the:

• axle.

• pulley.

• wheel.

• pivot.

Answer explanation

The centre of a wheel and axle is the axle, which serves as the central shaft that the wheel rotates around. The wheel is attached to the axle, but the axle itself is the pivotal component.

A pulley is:

• a type of gear.

• a wheel and axle.

• a type of load.

• a speed multiplier.

Answer explanation

A pulley consists of a wheel that rotates around an axle, allowing it to change the direction of force applied to a rope or cable. This makes 'a wheel and axle' the correct description, unlike the other options.

The more pulleys in a system, the:

• greater the distance you have to move.

• greater the force you need to apply.

• less you need rope.

• less distance you have to move.

Answer explanation

The more pulleys you have, the greater the distance you must pull the rope to lift the load. This is because the mechanical advantage gained from pulleys allows you to lift heavier loads, but requires more rope movement.

A machine that consists of two or more simple machines is called:

• a multi-gear.

• a complex machine.

• a compound machine.

• a confounding machine.

Answer explanation

A machine that consists of two or more simple machines is called a compound machine. This term accurately describes the combination of multiple simple machines working together.