Text book Exercise:
Q1: Give two examples each, of modes of transport used on land, water and air.
Ans: Two examples of each.
Land transport: bus and train.
Water transport: boat and ship.
Air transport: Helicopter and aeroplane.
Q2: 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______________.
Ans:
(i) 100
(ii) 500
(iii) periodic motion
(iv) periodic motion
(v) rotational motion
Q3: Why can a pace or a footstep not be used as a standard unit of length?
Ans: Standarrd unit of length must have a fixed numeric value while footstep does have so.
Q4: Arrange the following lengths in their increasing magnitude:
1 metre, 1 centimetre, 1 kilometre,1 millimetre.
Ans: 1 milimetre, 1 centimetre, 1 metre, 1 kilometre
Q5: The height of a person is 1.65 m. Express it into cm and mm.
Ans:
The height of a person = 1.65 m
In centimetre,
1 metre = 100 cm
1.65 m = 1.65 x 100 cm
= 165 cm
In milimetre,
1 centimetre = 10 milimetre
1 metre = 100 centimetre
Or = 100 x 10 milimetre
= 1000 milimetre
1.65 metre = 1.65 x 1000 milimetre
= 1650 milimetre
Q6: The distance between Radha's home and her school is 3250 m. Express this distance into km.
Ans:
Q7: 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?
Ans:
Reading of scale at one end = 3.0 cm
Reading of scale at other end = 33.1 cm
Distance between two end = 33.1 - 3.0 cm
= 30.1 cm
Q8: Write the similarities and differences between the motion of a bicycle and a ceiling fan that has been switched on.
Ans: Similarities: the motion of a bicycle and a celing fan both have circular motion. Differences: The bicycle moves on straight line but ceiling fan does not move so.
Q9: 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?
Ans:
Q10: Give two examples of periodic motion.
Ans:
(i) The motion of child on a swing.
(ii) moving here and there the branches of tree.
