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2.7.. Being Aware of The Need for Safety Features in Vehicles

& 2.11.. Appreciating The Importance of Maximising The Effiency of Devices Name: Noorhaida Binti Mohd Jusrin Class: 4 Rajin Teacher Name: Miss Shim Geek Ling

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2.7. Being Aware of The Need For Safety Features in Vehicles.[ 1-3 ] 2.11. Appreciating The Importance of Maximising The Effiency of Devices. [ 46]

2.7. BEING AWARE OF THE NEED FOR SAFETY FEATURES IN VEHICLES

1) Advanced in Technology have made it possible for vehicles nowadays to be built with various safety features. 2) This can reduce the damage and injury caused by high impulsive forces during collision. 3) Figures 2.7.1. Shows the safety features in a vehicles.

Figure 2.7.1

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The Safety Analysis From The Motion

1) A driver notices a boy crossing the road suddenly. He quickly brakes the car. As Shown in the Figure 2.7.2

Figures 2.7.2

2) Whether or not the car will hit the boy depends on its distance, speed, thinking distance and also braking distance. 3) It takes time for he driver to react before he brakes the car. In this fraction of a second, the car still travels a short distance at a constant speed, v. his called the ‘thinking distance’.

4) The car will still travel a short distance after the brake is pressed. This is called the ‘braking distance’. The car decelerates. 5) The total stopping distance = Thinking distance + Braking distance

Figures 2.7.3. Stopping distance = thinking distance + braking distance

6) On a dry road. With good brakes and normal reaction time, the stopping distance will be the following patterns.

Figure : 2.7.4

7) The Braking distance the car covers from the moment the driver is aware of the need to stop to the point at which the vehicles comes to a complete halt. The Thinking Distances Increase The Braking Distance Increase when when 1) The driver takes drugs and alcohol. 1) The car is heavier. 2) The driver is tired.

2) The road is wet or smooth. 3) The road is poorly maintained. Table : 2.7.1

2.11. APPRECIATING THE IMPORTANCE OF MAXIMISING THE EFFICIENCY OF DEVICES

Figure 2.11.1 : The Various Energy Convertors

1) Figures 2.11.1 shows the 3 energy converting devices that receive energy in one from and transform in into another useful form.

The Process of Transforming The Input Energy Into The Output Energy. 

1) Some of the input energy is always transform into unwanted forms of energy. 2) Therefore, the efficiency of energy convertors is always less than 100%. 3) We often have to pay for the input energy used by a device. For the example, the driver of a car has to pay for

the petrol to be used by the car engine while he cost of the electrical energy we use every day is shown in the monthly electricity bill. 4) Both the useful output energy and unwanted energy are lost to the surroundings.

Figure 2.11.2 : Sankey Diagram For The Energy Conversions in The Operation of a Car

5) Since the energy resources in his world are limited, it is very importance that a devicemakes the best possible use of the input energy.