Question 1. Give two examples of each of the modes of transport used on land, water and air.
Solution 1. Land- car, bus, trains, scooter
Water- ship, boat
Air- Aeroplane, helicopter
Question 2. Fill in the blanks:
- One metre is ______ cm.
- Five kilometre is ________ m.
- Motion of a child in a swing is ________.
- The motion of the needle of a sewing machine is _______.
- Motion of wheel of a bicycle is ________.
Solution 2.
- One metre is 100 cm.
- Five kilometres is 5000 m.
- The motion of a child in a swing is periodic motion.
- The motion of the needle of a sewing machine is periodic motion.
- The motion of the wheel of a bicycle is circular motion.
Question 3. Why can a pace or a footstep not be used as a standard unit of length?
Solution 3. A pace or a footstep not be used as a standard unit of length because everyone has a different pace or footstep.
Question 4. Arrange the following lengths in their increasing magnitude:
1 metre, 1 centimetre, 1 kilometre, 1 millimetre.
Solution 4. The increasing order is:
1 millimetre < 1 centimetre < 1 metre < 1 kilometre
Question 5. The height of a person is 1.65 m. express it in cm and mm.
Solution 5. a) 1.65 m = 1.65*100 cm = 165 cm
- b) 1.65 m = 1.65*1000 mm = 1650 mm
Question 6. The distance between Radha’s home and her school is 3250 m. Express this distance into km.
Solution 6. 1km = 1000 m
Hence 3250 m = 3250/1000 = 3.25 km
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?
Solution 7. Length of needle = 33.1 – 3 = 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.
Solution 8. Similarities: the motion of both a bicycle and a ceiling fan exerts circular motion.
Differences: The fan does not move in rectilinear motion whereas the bicycle shows 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?
Solution 9. An elastic tape cannot give an accurate measurement of the distance because it varies in size and length when it is stretched. It would be difficult to tell someone about a distance measure with elastic tape as we have to inform the other person how much did we stretch the tape.
Question 10. Give two examples of periodic motion.
Solution 10. Following are the two examples of periodic motion:
- oscillations of a pendulum.
- The motion of swing/motion of the earth around the sun.