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Chapter 10 Motion and Measurement of Distances

Question 1: Give two examples each, of modes of transport used on land, water and air.

Land - Car, Bus
Water - Ship, Boat
Air - Plane, Helicopter

Question 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______________.

i) One metre is 100 cm.
ii) Five kilometre is 5000 m.
iii) Motion of a child on a swing is periodic.
iv) Motion of the needle of a sewing machine is periodic.
v) Motion of the wheel of a bicycle is circular.

Question 3: Why can a pace or a footstep not be used as a standard unit of length?
A pace or a footstep cannot be used as a standard unit of length as it varies from person to person. And therefore, the standard unit of length is meter which is 100 cm.

Question 4: Arrange the following lengths in their increasing magnitude:
1 metre, 1 centimetre, 1 kilometre, 1 millimetre.

1 millimetre, 1 centimetre, 1 metre, 1 kilometre

Question 5: The height of a person is 1.65 m. Express it into cm and mm.

Height of a person (in meter) = 1.65 m
Height of person (in centimetre) = ?
= 1 m = 100 cm
= 1.65 m = 1.65 × 100
= 1.65 m = 165 cm

Height of person (in meter) = 1.65 m
Height of person (in millimetre) = ?

= 1 m = 1000 mm
= 1.65 m = 1.65 × 1000
= 1.65 m = 1650 mm

Question 6: The distance between Radha's home and her school is 3250 m. Express this distance into km.

Distance between Radha’s home and her school (in meter) = 3250 m
Distance between Radha’s home and her school (in kilometre) = ?
Let the distance between Radha’s home and her school (in kilometer) be x.

= 1 km = 1000 m
= x = 3250 m
= x = 3250/1000
= x = 3.25 km

Therefore, the distance between Radha’s home and her school is 3.25 m.

Question 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?

Length of the reading of the scale at one end = 3.0 cm
Length of the reading of the scale at another end = 33.1 cm
Length of needle = ?

= Length of needle = Length of the reading of the scale at another end - Length of the reading of the scale at one end
= Length of needle = 33.1 cm - 3.0 cm
= Length of needle = 30.1 cm

Therefore, the length of the knitting needle is 30.1 cm.

Question 8: Write the similarities and differences between the motion of a bicycle and a ceiling fan that has been switched on.

→ Similarities - The blades of a fan and the wheels of a bicycle shows circular motion
→ Differences - Bicycle move in rectilinear motion, but the fan does not move in rectilinear motion.

Question 9: 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?