Engineering Jc 24/25

What are the four strokes in a petrol engine's four-stroke cycle?

1. Induction stroke, 2. Compression stroke, 3. Power stroke, 4. Exhaust stroke.

What occurs during the induction stroke of a petrol engine?

The piston moves down the cylinder with the inlet port open and the exhaust port closed, filling the cylinder with a mixture of petrol vapour and air.

What happens during the compression stroke of a petrol engine?

The piston moves up the cylinder with both ports closed, compressing the mixture at the top end of the cylinder.

Describe the power stroke in a petrol engine.

At the end of the compression stroke, an electric spark ignites the petrol vapour, causing a rapid burn that forces the piston down the cylinder.

What is the function of the exhaust stroke in a petrol engine?

The piston returns up the cylinder with the inlet port closed and the exhaust port open, expelling the gases from the cylinder.

What is the role of the spark plug in a petrol engine?

The spark plug creates an electric spark that ignites the petrol vapour in the combustion chamber.

What type of vehicles typically use a four-stroke petrol engine?

Cars.

What is a two-stroke engine commonly used for?

Small machines such as strimmers, lawnmowers, and scooters.

How does a two-stroke engine differ from a four-stroke engine?

A two-stroke engine combines the strokes into two phases, making it simpler

What type of engine is commonly used in trucks and buses?

Diesel engine.

What are the advantages of using diesel fuel in engines?

Diesel provides more pulling power or torque.

What is a key environmental difference between diesel and petrol engines?

Diesel engines produce more air particle pollutants but less CO2, as they burn less fuel.

What is the main disadvantage of a two-stroke engine compared to a four-stroke engine?

It is not as powerful as a four-stroke engine.

Strength

the ability to maintain shape under the application of force

brittleness

Breaks easily when impacted

hardness

difficult to scratch or indent

Elasticity

can be deformed a lot and still return to its original state

Ductility

will stretch a lot under a pulling force

malleability

will flatten easily under a squashing force

Toughness

both strong and not brittle, difficult to break, it absorbs energy of impacts by deforming but still wont break

Transparency

see through - opposite is opaque

weight

how heavy an object is

Battery

powers an electric current

Switch

Switches a circuit ON/OFF

LED (Light Emitting Diode)

Allows current in one direction only and gives off light

Resistor

Slows down the flow of current, protecting delicate components

Lamp

Gives off light

Capacitor

Stores electric charge

Light Dependant Resistor

Resistance drops with increasing light; used in street lights

Motor

Provides Power/Drive, used in models, printers, etc.

Voltmeter

Measures Voltage

Ammeter

Measures Current

Variable resistor

Used in speed/volume control. Also in dimmer switches