Form 5_Science _Chp 5

7/28/2019 Form 5_Science _Chp 5

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Motion Chapter 5 (Arena Gemilang 2013) By Mr.Selva Page 1

5.1 Structure and Operational Principle of vehicles with Engines

Vehicles with engines

Petrol enginesDiesel engines

Both engines uses the same principle of operation:

PUSAT TUISYEN ARENA GEMILANG 2013

FORM 5 CHAPTER 5 (MOTION)

Do you know ????

Like most engines, rockets burn fuel. Most rocket engines turn the fuelinto hot gas. The engine pushes the gas out its back. The gas makes the

rocket move forward.

Fuel burn in the engine Heat produce expands

gasesPressure produce

pushes the piston

The piston turn the

vehicles wheels.

By Mr.Selva


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Four-Stroke Petrol Engine:


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Four-Stroke Diesel Engine.

Most heavy vehicles such as lorries and buses will use four stroke engines.

The main difference between a diesel and petrol engine is:

A. Only air get into the cylinder during the intake stroke.B. Diesel engines do not use spark plugs to light fuel.Fuel is lit up by very high temperature due

to air compression.

Two Stroke Petrol Engine


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Relationship between the structure and operation of the engine to the movement of vehicles.

Energy Transmission System:

Gear Box Connect crankshaft to driveshaftGear system control speed of the car (low gear-high power) and (high gear-faster speed)

Axle Connected to driveshaftClutch Separate the engine from gearboxDriveshaft Connected to crankshaft when gear in useCar accelerator Control speed and connected to fuel systemBrake system Used to stop the car and have two types

Disc brake and drum brake.


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Ticker Timer


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Worked Example 1:

The ticker tape graph shown below is obtained in an experiment using a moving trolley and ticker timer.(50Hz current).Calculate the average velocity of the trolley.

Worked Example 2:

The ticker tape graph shown below is obtained in an experiment using a moving trolley down aninclined plane. Calculate the average acceleration of the trolley.


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Moving Inertia Static InertiaMoving inertia is possessed by a moving object. It

resists any force trying to slow it down, make it gofaster or change its direction of motion.

Stationary inertia is the inertia possessed by a

body at rest.


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Hydraulic Brake Illustration

1. When the drivers footpresses on the brake pedal,the pressure exerted on thebrake fluid is transmittedunchanged to the four wheelcylinders.

2. This pressure acting on alarge of the piston in thecylinder produces a largeforce on the piston.

3. 3. This force pushes thebrake pads outwards topress on the rotating drumor rotating disc and slowdown or stop the motor vehicle.


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Hydraulic Jack Illustration1. A hydraulic jack uses a

small force to lift acompressor very largeforce such as a motor car.

2. When the compressor isswitched on, the air pressure on the smallcylinder, causing the largepiston to rise.

3. The pressure on the oil inthe small piston istransmitted unchanged tothe large cylinder

4. 4. This pressure acting ona large surface of the largepiston produces a big forcewhich pushes the car up.

5.7 Motion of Vehicles in Water.

Principle of Operation of Vehicles in Water

Vehicles without engines

Sampans and canoes are moved through water by using human energy. Sailing ships are moved by using the kinetic energy of wind

Ship A ship is driven by an engine which turns the propellers.

The turning propellers push the water behind (action) and causesa forward momentum (reaction) which drives the ship forward.

The rudder of the ship controls the direction of motion of the ship.Hovercraft A hovercraft moves on a cushion of air on the surface of the

sea.

The engine turns the fans which produce the cushion of air to liftthe hovercraft from the sea.

The large fans on top of the hovercraft produce a strongbackward wind (action) which causes an equally strong forwardmomentum in (reaction) that pushes the boat forward.


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Hydrofoil The lower surface of a hydrofoil has wing-shaped structurescalled hydrofoils.

At a certain speed, the hydrofoils get lifted above the water surface (aerofoil principle) and the boat moves faster becauseof reduced friction with the water

Archimedes Principle

When a body is immersed in a fluid (gas or liquid), it experiences a loss in weight (up-thrust)equal to the weight of the fluid displaced by the body.

When the ballast tanks of a submarine are filled with sea water, the submarine becomes denseand submerges in the sea.

When the ballast tanks are emptied, the submarine becomes less dense and rises to thesurface of the sea. This is because the weight of the submarine is now equal to the upthrust


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5.8 Motion of Vehicles in the Air.

The Jet Engine

Air is sucked from the front of the engine into the compressor and compressed so that it containsmore oxygen for its volume.

The hot compressed air is directed into the combustion chamber where a fuel such as kerosene is

sprayed into it.

3. The mixture of hot air and fuel burns and releases hot exhaust gases, which escape from the backof the engine and produce a great backward momentum (action).

4. This action causes as equally large forward momentum (reaction) which pushes the jet planeforward.

The Rocket Engine

1. Liquid hydrogen and liquid oxygen are carried in the rocket engine.2. The hydrogen fuel burns fiercely in the oxygen in the combustion

chamber producing exhaust gases.3. The exhaust gases escape from the back of the engine with

great backward momentum (action).4. This action causes an equally powerful forward momentum

(reaction) which pushes the rocket upwards.5. Unlike a jet plane, a rocket can move outside the Earths

atmosphere because it carries its own hydrogen and oxygen.


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Form 5_Science _Chp 5

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