1000 questions & answers

Fill in the blanks:
(i) One metre is ______________ cm.
(ii) Five kilometres 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 can a pace or a footstep not be used as a standard unit of length?

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.

The distance between Radha's home and her school is 3250 m. Express this distance into km.

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?

Write the similarities and differences between the motion of a bicycle and a ceiling fan that has been switched on.

Why would you not like to use a measuring tape made of an elastic material like rubber to measure distance? What would be some of the problems you would meet in telling someone about a distance you measured with such a tape?

Give two examples of periodic motion.

Rearrange the boxes given below to make a sentence that helps us understand opaque objects.

Classify the objects or materials given below as opaque, transparent or translucent and luminous or non-luminous: Air, water, a piece of rock, a sheet of aluminium, a mirror, a wooden board, a sheet of polythene, a CD, smoke, a sheet of plane glass, fog, a piece of red hot iron, an umbrella, a lighted fluorescent tube, a wall, a sheet of carbon paper, the flame of a gas burner, a sheet of cardboard, a lighted torch, a sheet of cellophane, a wire mesh, kerosene stove, sun, firefly, moon

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?

In a completely dark room, if you hold up a mirror in front of you, will you see a reflection of yourself in the mirror?

Make a row of your friends — A, B, C and D, standing in a line. Let one friend stand in front facing them and holding out a mirror towards them (Fig. 8.10).
Now, each person can tell who they are able to see in the Mirror. A, B, C, or D. If, A is able to see B in the mirror then, can B also see A in the mirror? Similarly, for any two pairs amongst A, B, C, or D? If A is not able to see B in the mirror, then is B able to see A in the mirror?
Similarly, for any two pairs amongst A, B, C, or D? This activity tells us something about the way light travels and gets reflected from mirrors. You will learn more about this in higher classes.

Fill in the blanks :
(a) A device that is used to break an electric circuit is called _______________.
(b) An electric cell has _______________ terminals.

Mark 'True' or 'False' for the following statements:
(a) Electric current can flow through metals.
(b) Instead of metal wires, a jute string can be used to make a circuit.
(c) Electric current can pass through a sheet of thermocol

Explain why the bulb would not glow in the arrangement shown in Fig. 9.13.

Complete the drawing shown in Fig. 9.14 to indicate where the free ends of the two wires should be joined to make the bulb glow.

What is the purpose of using an electric switch? Name some electrical gadgets that have switches built into them.

Would the bulb glow after completing the circuit shown in Fig. 9.14 if instead of safety pin we use an eraser?