Here are the steps to solve these speed problems: 1. Time taken = 10.30 - 8.30 = 2 hours Distance = 140 km Speed = Distance/Time = 140 km/2 hours = 70 km/h 2. Distance = 8 m Time = 2 s Speed = Distance/Time = 8 m/2 s = 4 m/s 3. Car A: Distance = 300 km, Time = 3 hours Speed = Distance/Time = 300 km/3 hours = 100 km/h Car B: Distance = 300 km, Time = 4 hours Speed = Distance/Time = 300 km/4 hours = 75 km/h

2.  A force is a push and pull
 All the daily life activities involve push and
pull.
 Force can not be seen but can be felt.

3. 1. Force can change shape of an object.
2. Force can cause a stationary object to
move
3. Force can change speed of a moving
object.
4. Force can change direction of the moving
object.

4.  Friction is a type of force that opposes the
movement of an object.
 It always acts in the opposite direction to the
movement of an object.
 Friction occurs when two surfaces are
contact with each other.

5. 1. Produces heat
- When we rub our palms together, the palms
become warmer because friction produce
heat.
2. Opposes motion
- When a toy car is given a push, it will
move. However, its movement become
slower and slower. After sometimes, it will
stops. This is due to the friction between
its tyres and the floor opposing the motion
of the toy car.

6. 3. Causes wear and tear
- When a pair of shoes is frequently used, the
shoes will wear out. The rubbing surfaces
between the soles and floor causes the shoes
to wear out. Brakes, tyres and engines also
wear out after some time due to friction.

7. The amount of friction depends on:
1. The types of surfaces
- If the surface is rough, it will produce more
friction than the smooth surface.
2. The mass of an object
- If the mass of an object is bigger, it will
produce more friction than the small mass
object.

8. 1. Using the round and smooth objects like
rollers and ball bearings.
2. Using the lubricants like oil, grease and
wax.
3. Using air cushion.
4. Using the fine powder.

9.  Holding things firmer in place
 Slowing down or stopping moving objects
 Providing better grip on surfaces
 Friction can be increased by increasing the
roughness of the contact surfaces.

10.  Enables to hold things in our hand
 Enables objects to stay in place
 Produces heat
 Wears out rubbing surfaces for example
between the knife and the stone.

11.  Friction opposes and slow down the motion,
we need to apply force.
 As the friction produce heat, the heat
produced may spoil the engine. Cooling
system must be provided to remove the heat.
 The friction also cause wear and tear. Tyres
and break pads in vehicles need to be
replaced from time to time.

12.  Speed is the measurement of how fast an
object moves.
 Object that moves faster has greater speed.
 Object that moves slower has lower speed.

13.  Object that moves faster:
a) Travel longer distance in a given time
b) Takes a shorter time to travel a given
distance.

14.  Calculation of speed is as follow:
Speed = distance travelled
time taken
 to calculate speed, we need to know
a) The distance travelled by the object
b) The time taken to travel the distance

15. Sam kicked a ball. The ball moved 9 meters
in 3 seconds. What is the speed?
Speed of the ball = distance travelled
time taken
Speed = 9 m
3s
= 3m/s

16. 1. A bus started its journey from Kuala
Lumpur at 8.30 a.m. It reached Tampin,
which is 140 km away from Kuala Lumpur,
at 10.30 a.m. What is the speed?
2. A ball rolls 8 meters in 2 seconds. What is
the speed of the ball?
3. There are two cars. The cars travelled the
same distance from Johor Bahru to Kuala
Lumpur. The distance is 300 km. Car A,
travelled within 3 hours while car B
travelled within 4 hours. Calculate the
speed of both cars.