Simple Machines pre-test

Which statement about simple machines is not true?

• They often act to increase the amount of force applied to an object.

• They often require electricity or a motor.

• They make jobs easier to perform.

• They give a mechanical advantage.

Answer explanation

The statement 'They often require electricity or a motor' is not true for simple machines, as many operate solely on mechanical principles without needing electrical power.

Which row matches the terms with their definitions? Effort | Load | Load force

• how hard the person using the simple machine tries | object being moved | weight of the object being moved

• object being moved | amount of force required | weight of the object being moved

• the force applied by the user | the force applied to the load | amount of force required to move the load

• object being moved | mechanical device to apply the force | amount of effort required to move the load

Answer explanation

The correct choice matches each term accurately: 'the force applied by the user' corresponds to Effort, 'the force applied to the load' corresponds to Load, and 'amount of force required to move the load' corresponds to Load force.

Which of these objects are levers?

• wheelbarrow

• scissors

• spoon being used to open a tin

• all of these

Answer explanation

All the objects listed are levers. A wheelbarrow uses a lever to lift loads, scissors operate on a lever principle to cut, and a spoon can act as a lever when prying open a tin. Therefore, the correct answer is 'all of these'.

How many different classes of lever are there?

• one

• two

• three

• four

Answer explanation

There are three classes of levers: first class, second class, and third class. Each class is defined by the relative positions of the effort, load, and fulcrum. Therefore, the correct answer is three.

What is the name for the orange triangle (the fixed point on which the lever pivots)?

• load

• fulcrum

• effort

• lever

Answer explanation

The orange triangle is called the fulcrum. It is the fixed point on which the lever pivots, allowing it to lift or move a load with the application of effort.

Which class of lever is depicted in the diagram?

• class 1 lever

• class 2 lever

• class 3 lever

• class 4 lever

Answer explanation

A class 1 lever has the fulcrum positioned between the effort and the load. This configuration allows for a balance of forces, making it easier to lift the load, which is characteristic of the lever depicted in the diagram.

What does this type of lever multiply?

• speed of the movement

• force of the movement

• size of the movement

• duration of the movement

Answer explanation

This type of lever multiplies the force of the movement, allowing a smaller input force to lift a heavier load. It is designed to enhance the effectiveness of the applied force.

A ramp (inclined plane) is a force multiplier, because an object can be pushed more easily up a ramp than lifted straight up into the air. Which of the following features would not increase the mechanical advantage of an inclined plane?

• steeper incline over a shorter distance

• gentler incline over a greater distance

• increasing the effort force pushing the object up the ramp

• wheels or rollers to reduce friction

Answer explanation

Increasing the effort force does not enhance the mechanical advantage of the ramp; it simply makes it harder to push the object. A gentler incline or reducing friction would improve the mechanical advantage.

Driving a wedge such as an axe head enables you to split a piece of wood into two pieces. How does it change the force?

• It multiplies the force, meaning you need to use more effort.

• It multiplies the speed, meaning you need to use less effort.

• It changes the direction of the force. The downwards force produces forces perpendicular (at a right angle) to the inclined planes on each face of the axe.

• The downwards force is transferred straight down the centre of the wood, splitting it in half.

Answer explanation

The correct choice explains that the axe changes the direction of the force. The downward force creates perpendicular forces on the axe's inclined planes, effectively splitting the wood apart.

Observe the single fixed pulley system in operation here. What is the mechanical advantage of the system?

• impossible to tell

• 1/2

• 2

• 1

Answer explanation

In a single fixed pulley system, the mechanical advantage is always 1. This means the effort force equals the load force, providing no gain in force, only a change in direction. Thus, the correct answer is 1.