Calculation of Speed
FIRDAUS RIPIN
Calculation of Speed
1. The speed of an object can be calculated using the following formula.

Distance travelled
Speed = --------------------------------------
Time taken

2. Units for speed are as follows.
(a) Centimetres per second (cm/s)
Distance travelled in centimetres by an object in one second
(b) Metres per second (m/s)
Distance travelled in metres by an object in one second
(c) Kilometres per hour (km/h)
Distance travelled in kilometres by an object in one hour


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Relationship between Speed and Time
FIRDAUS RIPIN
Relationship between Speed and Time
1. To determine which object is faster, we can compare the time taken by the moving objects to travel in given distance.
2. The object which moves faster takes a shorter time to travel a given distance.

Hubungan antara Kelajuan dan Masa
1. Untuk menentukan objek mana yang bergerak lebih laju, kita boleh bandingkan masa yang diambil oleh objek untuk bergerak dalam jarak yang ditetapkan.
2.Objek yang lebih laju mengambil masa yang lebih pendek untuk melalui jarak yang ditetapkan.
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Relationship between Speed and Distance
FIRDAUS RIPIN
Relationship between Speed and Distance
1. To determine which object moves faster, we can compare the distances travelled in a given time by two moving objects.
2. The object which moves faster travels a longer distance in a given time.

Hubungan antara Kelajuan dan Jarak
1. Untuk menentukan objek mana yang bergerak lebih laju, kita boleh bandingkan jarak yang dilalui dalam tempoh tertentu oleh kedua-dua objek.
2. Objek yang bergerak lebih laju melalui jarak yang lebih panjang dalam tempoh yang ditetapkan.
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Speed
FIRDAUS RIPIN
What is speed?
1. Speed is the distance travelled by an object per unit time.
2. Speed shows how fast an object moves.
3. Every moving object has speed. Only stationary objects have no speed.
4. The speed of a moving object can change. For example, a car can move fast or slow at different times.
5. Different objects have different speeds.

Apakah kelajuan?
1. Kelajuan ialah jarak yang dilalui oleh suatu objek dalam satu unit masa.
2. Kelajuan menunjukkan kepantasan objek bergerak.
3. Setiap objek yang bergerak mempunyai kelajuan. Hanya objek yang pegun tidak mempunyai tidak mempunyai kelajuan.
4. Kelajuan objek yang bergerak boleh berubah. Contohnya kereta boleh bergerak dengan laju atau perlahan pada masa yang berbeza.
5. Objek yang berbeza mempunyai kelajuan yang berbeza.
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Ways to Increase Friction
FIRDAUS RIPIN

1. Friction is also very important in everyday life.
2. We need to increase friction fo safety.
3. Ways to increase friction are follows.
(a) Patterns on the surface of tyres and on the soles of shoes
(b) A carpet is used to cover the tiled surface.
(c) Road are made with rough surfaces to provide grip fo vehicle tyres.
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Ways to Reduce Friction
FIRDAUS RIPIN



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Ways to Reduce Friction
FIRDAUS RIPIN
1. Friction cannot be eliminated.
2. Otherwise, friction can be reduced by using certian material as follows.
(a) Rollers
(b) Talcum powder
(c) Oil, wax, grease
(d) Air cushion
3. Rollers are found in many objects such as roller blades, trolleys, chairs and skateboards. They reduce friction by reducing contact between moving surfaces.
4. Oil, wax, grease and talcum powder are used as lubricants to reduce friction, so moving surfaces slide smoothly over one another. For example, oil is used to reduce friction between door hinges.
5. An air cushion (layer of air) under a hovercraft enables a hovercraft to glide easily above water.
6. Aircraf and traina are designed to have aerodynamic shapes to reduce friction friction so that air flows smoothly. Smooth air flow means that less fuel is needed for higher speeds.
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Disadvantages of Friction
FIRDAUS RIPIN

1. The disadvantages of friction are as follows.


(a) Slows down or stops the movement of objects
A bigger force is needed to overcome the friction so that an object can move faster.

For example, a bicycle will eventually stop if it not cycled consistently. if you want make the bicycle speed up, you have to cycle it faster. That means more energy is needed to overcome the frictional force.


(b) Causes the surface of an object to wear out - for example, soles of shoes and surfaces of tyres.
(c) Produces unnecessary heat - Car engines becomes hotter because of friction.

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Advantages of Friction
FIRDAUS RIPIN


1. Frictional force brings many advantages and disadvantages in our lives.
2. The advantages of friction are as follows.
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Factor that Affect Friction
FIRDAUS RIPIN



1. The factors that affect friction are:
(a) the condition of the surfaces in contact
(b) the weight of an object

2. A rough surface produces greater friction compared to a smooth surface.
(a) For example, it is harder to push or pull a heavy box along a carpet than along a tiled surface.
(b) The carpet produces greater frictional force than the tiled surface.
(c) The huge amount of frictin force impedes the box movement, making it very difficult to be moved.

3. We are more likely to slip while walking on a wet floor. This is because the wet floor is slippery and produces less friction.

4. Friction also depands on the weight of an object.
(a) A heavier object exerts a greater frictional force.
(b) Therefore, a bigger and heavier box is more difficult to be moved than a smaller and lighter box.
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