Form

Form

4

Semester

1

Learning Area

Forces and Motion

Learning Objectives

Being aware of the need for safety features in vehicles

Duration

80 minutes

Prerequisite

1. Impulse and impulsive force

2. Effect of increasing and decreasing time of impact on the magnitude of the impulsive force

3. Beneficial impulsive force

Material Resources

Text book, lap top and LCD

Language Focus

Vocabulary(Refer to vocabulary list)

Method

Constructivism, Inquiry Learning, Discussion and Contextual

Noble values

Being thankful for the use of impulsive force in daily life

Learning Outcome

Teachers Activities

Students Activities

Questions and expected answers

Vocabulary

To relate the safety features in vehicles with impulsive force

To recall the equation of impulsive force

To define the equation of impulsive force

To identify the main factor to reduce the impulsive force

Safety features in vehicles

To solve problems involving impulsive force and the safety features in vehicles

ENGAGEMENT

Show video of collisions

Show graph of impulsive force vs time acting on a driver with and without wearing seat belts

EXPLORATION

If the time taken in a collision is longer, the impulsive force is reduced

EXTENSION

Ask students to sit in groups of 4-5.

Draw a car

Label safety equipment built into cars

Distribute a short article containing different kinds of safety equipment to students. [Appendix 1]

Recap lesson by telling all the safety equipment and its function.

i) Bumpers

To absorb impact in collision

ii)Front/rear part

Crumple in stages

iii)Air bags / SRS(Supplementary Restrain System)

To increase time action in collision

iv)Steering wheel

Easily crumpled to avoid serious injury

v)Dashboard

To lengthen the collision time

vi)Windscreen

Will not scattered easily

vii)Tyre

To control the stability

viii)Headrest

To protect during a collision/minimise head and neck injury

ix)Seat belts

To lengthen the collision time

x)Bonnet

Reduce the impulsive force on the pedestrian

xi)ABS

To prevent wheel lock-up when braking hard

EVALUATION

Distribute exercises to students [Appendix 2]

Pay attention to the video shown

Think

Observe the graph shown

Think and discuss

Sit in groups

Draw car and label the safety equipment

Each group gets a short article.

Identify and explain the safety equipment in the article

After 5 minutes, one member from each group will form a new group. The new group will have one member from the original group. (Jigsaw)

Carry out discussion and share different information on safety equipment

Add on information

Answer questions given

Teacher : What did you see?

Students : We saw different kinds of collision

Teacher : What were the dummies wearing?

Students : They were wearing seat belts.

Teacher : Why do we need to wear seat belts?

Students : To minimize injury and to prevent death

Teacher : So, never forget to wear the seat belt, do remind your parents!

Teacher : What is the equation for impulsive force?

Students : F=mv-mu

t

Teacher : How do seat belts and air bags prevent automobile injuries?

Students : Seat belts and air bags can increase time action in collision

Teacher : What is the factor that can be manipulated to reduce the impulsive force?

Students : Time action

Vocabulary

Seat belt-an arrangement of straps designed to hold a person steady in a seat

Bumper-a device for absorbing shock or preventing damage

Metal bar at either end of an automobile

Crumpled-to press, bend, or crush out of shape

Air bag-an automobile safety device consisting of a bag designed to inflate automatically especially in front of an

occupant in case of collision

Inflate-to swell or distend with air/gas

Windscreen-a screen that protects against the wind

Steering-a hand wheel by means of which one steers

wheel

Dashboard-a panel extending across the interior of a vehicle below the windshield containing dial and controls

Headrest-a support for the head

Head restraint

Appendix 1

Group 1

Read the passage below. Discuss in your group the safety features stated in the passage.

Safety Features in Vehicles

There are several safety features installed in a vehicle in order to reduce serious injury to the driver and passengers during collision. One of the safety equipment is the seat belt. Seat belt is an arrangement of straps designed to hold a person steady in a seat. Research has been carried out by the automobile companies to show the importance of seat belts.

By wearing the seat belt, the time action in a collision is lengthened. Thus, the impulsive force is reduced.

Bumpers are metal bar fixed at both ends of vehicle. They are installed at the front and rear parts of vehicles. They are devices used to absorb shock or prevent damages. When a collision occurs, the bumper crumple and thus lengthens the time action.

Group 2

Read the passage below. Discuss in your group the safety features stated in the passage.

Safety Features in Vehicles

An air bag is an automobile safety device consisting of a bag designed to inflate automatically especially in front of an occupant in case of collision. Nowadays, every automobile company installed air bags into their vehicles to reduce the injury to the driver and the passenger when a collision happens. The government has made a policy that all vehicles used in Malaysia must install air bags. This is due to the importance of the air bag. The air bag will inflate just as the car accelerates during an accident. Hence, the head of the driver which surge forward can be protected. The use of air bag will lengthen the time of the collision resulting in low impulsive force.

A steering wheel is a handwheel by means of which one steers a vehicle. It is made of material soft enough to lengthen the collision time and to cushion the momentum impact of the drivers head during an accident.

Group 3

Read the passage below. Discuss in your group the safety features stated in the passage.

Safety Features in Vehicles

The dashboard in a vehicle is a panel extending across the interior of a vehicle below the windshield containing dial and controls. It is normally made of material soft enough to lengthen the collision time when the head of the driver collides with it.

A screen that protects the driver and the passengers against the wind is called windscreen. It has anti-shattering properties so that during accidents the pieces of the screen chips will not be scattered easily as to hurt the driver or passengers.

Both the safety equipments mentioned above can reduce injury to the driver and passengers during an accident by increasing the collision time.

Group 4

Read the passage below. Discuss in your group the safety features stated in the passage.

Safety Features in Vehicles

Do you notice that the front or rear part of a car can be crumpled easily? Why do you think it is designed in such a way? This characteristic can increase the collision time during an accident. If the collision time is increased, the impulsive force is reduced.

The tyre of a car is normally broad and has a lot of friction grooves on it. Do you know why? This is to ensure a better control and the car is more stable.

Both front and rear parts of the car and tyres are designed to reduce the impulsive force acting on the driver and passengers during an accident. We should be thankful for these safety measures taken in vehicles in order to minimise serious injury and casualty during an accident.

Group 5

Read the passage below. Discuss in your group the safety features stated in the passage.

Safety Features in Vehicles

Headrest in vehicles is a support for the head, installed to cushion the head while the car is in motion. The neck of the driver and the passengers are protected especially during an accident.

Bonnet of a car is also one of the safety features in a vehicle. The Motor Company has invented new car which can reduce casualty in car accidents. When the car hits a pedestrian, the bonnet of the car will automatically spring upwards. This will prolong the collision time and hence reduces the impulsive force acting on the pedestrian.

ABS (Automatic Brake System) is installed to a car to prevent wheel lock-up when braking hard. Thus, the car will not spin and can avoid accident with other cars.

Appendix 2

Questions:

1. State 5 safety features normally installed in a car

2. A man of mass 60 kg is driving at a speed of 30 m s-1. The car stops after hitting a tree as shown.

a) If the driver did not wear the seat belt, calculate the impulsive force acting on the driver if the collision time is 0.05 s

b) If the driver wears seat belt, the time of collision is lengthen to 1.00 s. Calculate the impulsive force acting on the driver.

c) Which situation will the driver suffer serious injury most?

3. During a test on car safety, a dummy in a car is used to demonstrate the effects of a collision.

During the collision, the head of the dummy strikes the dashboard at 20 m s-1 as shown and comes to rest in 0.02 s. The mass of the head is 5 kg.

i) Calculate the average force exerted by the dashboard on the head of the dummy during the collision

ii) If the contact area between the head and the dashboard is

2

4

10

5

m

-

, calculate the pressure which this force produces on the head of the dummy

iii) The test on the dummy is repeated with an airbag which inflates during the collision. During the collision, the head of the dummy again travels forward at 20 m s-1 and is brought to rest bt the airbag.

Explain why there is less risk of damage to the head of the dummy when the airbag is used.

_1188322916.unknown