## Chapter 10 Motion and Measurement of Distances

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

Answer:

Answer:

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______________.

Answer:

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__.

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?**

Answer: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.

Answer:

**Question 4: Arrange the following lengths in their increasing magnitude:**

1 metre, 1 centimetre, 1 kilometre, 1 millimetre.

Answer:

1 metre, 1 centimetre, 1 kilometre, 1 millimetre.

Answer:

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.**

Answer:

Answer:

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.**

Answer:

Answer:

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?**

Answer:

Answer:

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.**

Answer:

Answer:

→ 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?**

Answer:Elastic tapes are stretchable. So, the length of an elastic measuring tape will change each time due to stretching. So, it will not give correct measurement of a distance. Therefore, we cannot use an elastic measuring tape to measure distance.

Answer:

**Question 10: Give two examples of periodic motion.**

Answer:

→ Motion of a child on a swing is periodic.

Answer:

→ Motion of the needle of a sewing machine is periodic.

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