Answer
Modes of transport used on land - Buses and Trains.
Modes of transport used on water - Ships and Boats.
Modes of transport used on air - Helicopters and Aeroplanes.
2. 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______________.
Answer
(i) One metre is 100 cm.
(ii) Five kilometre is 5000 m.
(iii)Motion of a child on a swing is periodic motion
(iv)Motion of the needle of a sewing machine is periodic motion
(v) Motion of wheel of a bicycle is circular motion
3. Why can a pace or a footstep not be used as a standard unit of length?
Answer
The length of pace or a footstep varies from person to person. If the length of footstep will be used as standard unit for measurement of length then two measured quantity will not be same. Hence, footstep or pace is not a constant quantity and cannot be used as a standard unit of length.
4. Arrange the following lengths in their increasing magnitude:
1 metre, 1 centimetre, 1 kilometre,1 millimetre.
Answer
1 millimetre > 1 centimetre > 1 metre > 1 kilometre
5. The height of a person is 1.65 m. Express it into cm and mm.
Answer
1.65 m = 1.65 × 100 cm = 165 cm
1.65 m = 1.65 × 100 × 10 mm = 1650 mm
6. The distance between Radha's home and her school is 3250 m. Express this distance into km.
Answer
1km = 1000 m
3250 m = 3250/1000 km = 3.25 km
7. 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?
Answer
The actual count of the length of the needle start from 3.0 cm instead of 0 cm. Thus, the actual length of the needle is (33.1 - 3.0) cm = 30.1 cm
8. Write the similarities and differences between the motion of a bicycle and a ceiling fan that has been switched on.
Answer
Similarities:
(i) Both the ceiling fan and the wheels of a bicycle show circular motion.
(ii) Both are fixed at point. Differences:
(i) A bicycle shows rectlinear motion while a ceiling fan does not.
9. 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?
Answer
An elastic tape is flexible and can be stretched. Thus, each time it will give different readings for the same length measured. Therefore, it is impossible to measure accurate distance from an elastic measuring tape.
10. Give two examples of periodic motion.
Answer
Two examples of periodic motion:
(i) Motion of a pendulum clock.
(ii) Motion of a swing.