MODIFICATION-SECTION BFORM 4

CHAPTER 1

1. Suitable ruler to use in laboratory

Suggestion ExplanationSmallest size scale 0.1 cm More accurateHigh accuracy Less error in measurementHigh consistency Low relative deviationsPlastic material Avoid parallax errorThin thickness Avoid parallax error

CHAPTER 2

2. Explain the suitability feature of arm exercise equipment.

Suggestion ExplanationSpring made of steel Can withstand higher forceTwo // more spring arrange in parallel

The spring system is stiffer

Spring with ticker wire Wire will not easily breakSmaller diameter coil of spring The smaller the diameter coil less elastic the

spring, so the arm exercise would not so hardChoose large force constant spring Will make strong spring, the spring will stiffer and

not broken easily

3. Suggest the suitable cloth , equipment and techniques to improve high jumper athlete and their safety .

4. Explain the characteristic of spring to make baby’s cradle.

Suggestion ExplanationChoose large force constant spring Will make strong spring, the spring will stiffer

and not broken easily.Choose large diameter of wire The larger diameter the stiffer the spring is.Large diameter coil of spring The larger the diameter coil more elastic the

spring isThe spring is made of steel or alloy Steel and alloy is stiffer than ironThe arrangement of spring is two or more line in parallel

The spring is stiffer

5. Explain the most suitable design of spring for shock absorber for motorcycles.

Suggestion ExplanationSmall diameter of spring coil Enough space for the springChoose large diameter of wire The larger the diameter the stiffer the springForce constant is more than 1000N Can support motorcyclist and passenger up to

100kgHigher spring constant Small compression of the springSmall natural frequency To reduce bumping, comfortable for user

6. Explain the simple characteristic of the rocket than can travel with greater acceleration.

Suggestions ExplanationsChoose metal with high strength and hardness

Even under pressure the shape will not change easily

Frame of rocket is made of low density metal

Lighter, can increase acceleration

Multistage rocket invented Each stage has burning fuel, pump and combustion chamber. It will slip off when fuel of each chamber completely burn. When the mass decreases, the acceleration increase

Rocket need to carry a tank of oxygen To enable the combustion of fuel in spaceSilver color rocket Reflect light efficiently so the temperature of

the rocket will not riseCover the body of rocket with heat insulator

Friction between air and body will increase heat. The insulator will reduce heat conductivity

Aerodynamic shape Reduce air friction, move faster

Suggestion ExplanationUse tight and light suit Less air fractionUse spikes shoes Better grip support while running and prevent

slipperyUse thicker mattress Increase time impact , reduce impulsive force .

prevent back injuryThe athlete have to sprint before jump

Can increase kinetic energy

Athlete have to bend the body during fall

Increase the time impact , reduce impulsive force

7. Suggest and explain the build of water bottle rocket in school competition to move higher altitude and has longer time on the air.

8. Give suggestion to improve the design of jet engine so that it can be use for larger airplane at the higher speed.

Suggestions ExplanationsIncrease more fuel injectors More fuel to be burnt to produce greater forceIncrease the size of the combustion chamber

More space for fuel to burnt

Decrease the diameter of the nozzle Exhaust gas ejected at higher velocityIncrease the speed of blade/use bigger blade

Increase the air intake

Blade and engine made of strong materials

Can withstand strong pressure and won’t break easily

9. Base on the physics principle, suggest the design of roller skate track so it can be used to oscillate skate continuously.

Suggestions ExplanationsSemicircular curve shape Exchange between kinetic energy and gravitational

potential easilySmooth surface Reduce frictional force/easy to slideThe slope slightly increase and decrease

Easy to oscillates cause by changing of energy

Use strong material such concrete of foundation of the track

Withstand high impact such as high force of jumping and landing

Soft layer at the surface Reduce impulsive force when landing, low risk if accident

10. Explain the most suitable design of motorcycle that can move fast, safe and save time in racing.

Suggestions ExplanationsLower seat height Lower center of gravity or more stable or safer to

turn.Bigger width of tire Bigger surface area, better support or low pressure

acts on the tires or more friction when breaks.Less thread pattern To decrease friction of tires to the road, can move

fastSmaller mass Lighter, can move faster or low inertiaWith ABS Motorcycle does not stop immediately or can be

controlled if direction changes or does not move sideways or more friction with ABS

Suggestions ExplanationsThe body of rocket must be tough Do not break easily in high pressure and when

landingSmaller mass Rocket will accelerate fasterThe shape is streamline/aerodynamic

Reduce air resistance

Nose cone or bullet shape on top of body

To improve the aerodynamic of rocket

45 angle of launching The rocket can travel maximum distanceThe volume of water is half or 1/3 from the whole volume

To increase momentum and impulsive force

Attach 3 or 4 fins at the tail of rocket space equally

Rocket will move smooth and stable

Attach parachute will make the rocket floating and has longer time on the air before landing//decrease the speed of falling due to air resistance

11. Suggest and explain how to make suitable beach motorcycle which able to move on the sand smoothly and comfortable.

Suggestions ExplanationsDeep thread patter // more definitive pattern

Better grip on sand, able to move smoothly on sand

Large tire (big surface contact with ground)

Reduce total pressure of car, increase stability and the car would not get stuck in the sand

Soft seat and water resistance Comfortable for cycles and would not get wet easilyExcellent resistance to rusting Everlasting. Would not rust easilyAttach shock absorber with higher spring constant and small natural frequency.

Reduce bumping, comfortable to cycle with

Low density body Lighter, would not stuck in sand

12. Suggest the suitable cloth and the best techniques to catch ball to prevent injury for goalkeeper.

Suggestion ExplanationsWear glove Reduce painful of the player’s hands when touching

the ball with big impulsive force.Use soft material for glove Lengthen the time impact, reduce impulsive force.Wear cloth which is made from material with moderate specific heat capacity

The cloth can absorb more heat when the player is sweating to maintain the temperature of player.

Base of shoes has stud Player give great pressure to make stud sink into ground and give stronger support without slipping.

When catching the ball, the goal keeper should move his hand backwards

This action lengthen the time impact between ball and hand, so it reduce the impulsive force.

The ball should have enough air pressure inside

Shorter the time impact between foot and ball, so impulsive force increase then the ball will has high speed and travel far away.

13. Using physics concept, suggest and explain suitable athlete’s attires, running, jumping, landing techniques and other aspects to help the long jumper can jump further.

Suggestion ExplanationUse tight and light suit Less air friction Use spike shoes Better grip support while running and prevent

slipperyThe athlete have to sprint before jump

Can increase the kinetic energy//momentum

The athlete have to push the body infront while jumping

Increase the elastic potential energy//able to increase longer distance of jumping

Athlete have to bent the body during fall

Increase the time impact, reduce impulsive force, less injured

14. Safety feature in car

Characteristic ExplanationThe bumper of car is prone to crash It will increase the time impact, the impulsive force

will reduceThe sitting space of the passenger is reinforced

To protect the passenger

Use safety belt During collision, safety belt will hold the passengers from thrown infront due to inertia

Use air bag Will inflate when accident occurs, the driver safe from hitting steering

Antilock breaking system(ABS) Allow car to stop quickly on slippery road and prevent from skidding

Strong steel struts Give good protection from side on collisionTire with tread Can stays contact with road, prever slippery

15. Explain the suitable loaded lorry which can carry liquid, such as petrol

Suggestion ExplanationThe load of lorry should be divided into many smaller tank

To reduce effect of inertia

The load must be tied So it will no fall of from the lorryFar gap distances between tractor and trailer

Prevent collision between tractor and trailer, easier when turning

Use more tire for lorry Pressure will be separate to all tires, able to carry more loads. Lower pressure better support and stability

Small belt behind lorry To discharge spark, safety reason to prevent from burning the petrol

Use antilock break system (ABS) The lorry can stop easily without skidding

16. Explain the design of and how kayak which can travel faster and safer.

Suggestion ExplanationStreamline /aerodynamic shape of body

Reduce water resistance

Smooth surface body /coated withwax

Reduce friction of body towards water

Low density material Lighter , easier to float, easy to carry and sail fasterStrong material body and peddle Everlasting , not easily brokenWider peddle surface Greater force because more water are peddled upWear safety jacket Passenger can float and safe if they fall into water.

17. Give suggestion to design a sail boat which can travel faster and smooth.

Suggestion ExplanationStreamline /aerodynamic shape of board

Reduce water and air resistance,can increase lifting

Smooth surface board/coated with wax

Reduce friction toward water

Low density material Lighter, easier to float and sail fasterStrong material Withstand strong wind, not easily damageWider sail Greater lifting force because more wind are

captured

18. Modified the ship that can carry more and heavier load, move faster and safe while travelling.

Suggestion ExplanationStrong material Can withstand great forceLow density material Light weightHas more than two stage,plimsoll line Safe to travel on the fresh and salt waterBig size Can place more goodsAerodynamic/streamline shape Reduce water friction.Waterproof sail Sail would not get e=wet easily.

19. Suggest how to increase the safety for motorbike racer to reduce injuries / accident

20. An earth-monitoring satellite falls into the earth’s atmosphere at a high velocity and reaches a high temperature. This is caused by the earth’s gravitational force and air resistance.Using the appropriate physics concepts, suggest and explain suitable designs or ways to protect the satellite and its equipment:

Suggestion Explanation Aerodynamic shape To reduce air resistance

Heat shield / material that is hard to burn

To protect the capsule

High melting point //ceramic Do not meltLanding in water // air bag Increase time of impact// Reduce impulsive forceLight material / / small mass // low density

-Reduce the inertia // -reduce the momentum //-reduce impulse

Parachute / /Retro rocket To reduce speedHard material // stiff composite Not easy to bend

Suggestion Explanation Use helmet To protect the headUse helmet with hard outer casing and soft inner liner

Helmet reduce head injuries in a crash by spreading the impact with hard outer casing and absorb energy with soft inner linear of styrofoam

Use safety jacket To protect the from injuries , cut ,burnUse gloves To protect the handUse padded leathers suit Will soften any impact and protect the skin from

abrasion

21. Explain how you would design the pile driving system.[the ram hammer is lifted to a height by the crane and allowed to fall on the pile.

Modification ReasonLarge hammer weight Large momentum when it hit the pileRam hammer made from hard material such as alloys

Not break easily/last longer

Hammer raised at higher position Inrease the gravitational potential energyStronger End of the top of the concrete pile

To avoid break at the top couse by the hammer

Sharp End of the bottom of the concrete pile

To increase the pressure

CHAPTER 3

22. Efficient brake system

Suggestions ExplanationsType of liquid: oil UncompressibleThickness of brake line :high To counter the high pressure from the liquidThe ratio of cross sectional area for wheel piston and master piston :high

To produce larger force on wheel piston

The chosen of type of brake for front rear wheel:Front wheel - discRear wheel - drum

Disc brake is more efficient than drum brake

23. Explain the design of hydrometer which can be use to determine a wide range of densities of liquid.

Suggestions ExplanationsSmall stem and long Increase sensitivity where the scale division are

far apart so that small changes in density can be detected

Glass wall Do not erode and small adhesive forceLarge diameter of bulb High up thrust / displaces more liquid / able to

float easilyScale can be made bigger or smaller than the density of water.[calibration]

- The hydrometer is floated in alcohol. The liquid level at the stem is marked (upper level)

- Then, the hydrometer is floated in higher density liquid like mercury and marked (lower level)

Ability to measure a wide range of densities of liquids.

Lead shots Hydrometer can stay upright

24. Describe the suitable design to build mobile tent for Sure Heboh event which will be construct at open space for a week. Using appropriate physics concept, suggests and explain.

Suggestion ExplanationChoose low density metal for frame Light weight and strongUse hollow rod which can assemble easily

Hollow rod is not heavy, but equally strong, easy to mobile anywhere, faster to build, can reduce the cost of construction and transport

Water proof canvas If raining, would not getting wetAntirust rod Can withstand rain and long lastingSharp end rod Small surface area, so higher pressure to ground,

yet the tent can be planted into ground firmly and stand still