Why can a pace or a footstep not be used as a standard unit of length?
A pace or a footstep not be used as a standard unit of length because its size of the foot can be increase with the time. Footsteps size is differ from person to person. So, it cannot be used as a standard unit of length.
Write the similarities and differences between the motion of a bicycle and a ceiling fan that has been switched on.
The distance between Radha's home and her school is 3250 m. Express this distance into km.
Fill in the blanks:
(i) One metre is ______________ cm.
(ii) Five kilometre is ______________ m.
(iii)Motion of a child on a swing is ______________.
(iv)Motion of the needle of a sewing machine is ______________.
(v) Motion of wheel of a bicycle is______________.
Why could you not use an elastic measuring tape to measure distance? What would be some of the problems you would meet in telling someone about a distance you measured with an elastic tape?
While measuring the length of a knitting needle, the reading of the scale at one end is 3.0 cm and at the other end is 33.1 cm. What is the length of the needle?
Arrange the following lengths in their increasing magnitude:
1 metre, 1 centimetre, 1 kilometre,1 millimetre.
The height of a person is 1.65 m. Express it into cm and mm.
Give two examples of periodic motion.
Give two examples each, of modes of transport used on land, water and air.
(a) Which kind of garbage is not converted into compost by the redworms?
(b) Have you seen any other organism besides redworms, in your pit? If yes, try to find out their names. Draw pictures of these.
Rearrange the boxes given below to make a sentence that helps us understand opaque objects.
To walk through a waterlogged area, you usually shorten the length of your dress by folding it. Can this change be reversed?
Do you find that all living beings need the same kind of food?
Name the major nutrients in our food.
Classify the following fibres as natural or synthetic:
nylon, wool, cotton, silk, polyester, jute
Name five objects which can be made from wood.
Why do we need to separate different components of a mixture? Give two examples.
Correct the following statements and rewrite them in your notebook.
(a) Stem absorbs water and minerals from the soil.
(b) Leaves hold the plant upright.
(c) Roots conduct water to the leaves.
(d) The number of petals and sepals in a flower is always equal.
(e) If the sepals of a flower are joined together, its petals are also joined together.
(f) If the petals of a flower are joined together, then the pistil is joined to the petal.
Fill in the blanks:
(a) Joints of the bones help in the ——————— of the body.
(b) A combination of bones and cartilages forms the _______ of the body.
(c) The bones at the elbow are joined by a ______________________ joint.
(d) The contraction of the _____________ pulls the bones during movement.
Draw (a) a leaf, (b) a taproot and (c) a flower, you have studied for Table 7.3.
Would the bulb glow in the circuit shown in Fig. 12.15?
It was observed that a pencil sharpener gets attracted by both the poles of a magnet although its body is made of plastic. Name a material that might have been used to make some part of it.
Match the items given in Column A with that in Column B
Column A Column B
Milk, curd, paneer, ghee eat other animals
Spinach, cauliflower, carrot eat plants and plant products
Lions and tigers are vegetables
Herbivores are all animal products
Do you find that all living beings need the same kind of food?
(a)Collect different kinds of packaging material. What was the purpose for which each one was used? Discuss in groups.
(b) Give an example in which packaging could have been reduced?
(c) Write a story on how packaging increases the amount of garbage.
Can you think of creating a shape that would give a circular shadow if held in one way and a rectangular shadow if held in another way?
What is winnowing? Where is it used?
Find the odd one out from the following:
a) Chair, Bed, Table, Baby, Cupboard
b) Rose, Jasmine, Boat, Marigold, Lotus
c) Aluminium, Iron, Copper, Silver, Sand
d) Sugar, Salt, Sand, Copper sulphate
To clean their spectacles, people often breathe out on glasses to make them wet. Explain why the glasses become wet.