Distance travelled (d) = 400 km
Time taken (t) = 5 hour
Average Speed (s) = \(\frac{d}{t}=\frac{400}{5}=80\) 
Average Speed = 80 kmph (or) Km/hr.

FUNCTIONS OF THE ROOT:
i) The root fixes the plant to the soil.
ii) Absorbs water and minerals from the soil.
iii) Stores food in some plants like Carrot and beetroot
FUNCTIONS OF THE STEM:
i) The stem supports the branches, leaves, flowers and fruits.
ii) Transports Water and minerals from roots to upper aerial plant parts.
iii) Transports the prepared food from leaves to other parts through stem.
iv) Stores food as in the case of sugarcane

When there is a change of position of an object with respect to time then it is called motion.
Types of motion:
a) Based on path:
i) Linear motion - a person walking on a straight path
ii) Curvilinear motion - throwing ball
iii) Circular motion - swirling stone tied to the rope
iv) Rotatory motion - a rotating top
v) Oscillatory motion - pendulum of clock
vi) Zig zag (or) Irregular motion - the motion of a bee
b) Based on duration:
i) period motion - movement of hour hand of a clock
ii) Non-periodic  - motion flapping of a flag in wind
c) Based on speed:
9) Uniform motion -  motion of a train at a constant speed
ii) Non-uniform motion - a vehicle moves in different speed

i) Birds have streamlined body covered with feathers. This body shape provides minimum resistance to air.
ii) They have a pair of wings to fly in the air.
iii) They have hollow and light bones.

Adaptive features of polar Bear : Thick skin for protection, White fur.
Adaptive features of Penguin : Paddle to swim, walk with two legs.

(i) By churning the curd, the solid butter will be collicted on the sides of the vessel.
(ii) The insoluble butter will be separated from the buttermilk and thus the buttermilk will be obtained.

(i) The atoms of a gas never stop moving.
(ii) They are not affected by gravity.
(iii) They spread out in order to occupy the available space.

1.  Millimetre
2.  Second
3. Error
4. Time
5. Mass
6. Average
7. Length
8. Odometer
9. Tape
10. Litre