Motion and Measurement of Distances
I.Give two example each of modes of transport used:
a) Land Transport – Buses and Trains
b) Water Transport – Ships and Boats
c) Air Transport – Helicopters and Aeroplanes.
II.Fill in the blanks:
i.
One meter 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
III Answer the following:-
1.Why
can a pace or a footstep not be used as a standard unit of length?
Ans:The length of pace or a footsteps various from person to person. If the
length of foot- steps will be the used as standard unit for measurement of
length then two measured quantity will not be same, Hence footsteps or pace is
not a constant quantity and cannot be used as a standard unit of length.
2.Arrange the following lengths in their increasing magnitude.1 metre, 1 centimetre, 1 kilometre, 1 millimetre Ans: 1 millimetre > 1 cemtimetre > 1 metre > 1 kilometre.
3.The height of a person is 1.65m Express it into cm and mm
Ans: 1.65 × 100 cm = 165 cm,
1.65m = 1.65 × 100 × 10 mm = 1650 mm
4.The
distance between Radhas home and her school is 3250m. Express this distance
into km
Ans: 1 km = 1000 m
3250 m = 325/100 km = 3.25 km.
5.While
measuring the length of a knitting needle the reading of the scale at one end
is 3.0cm and at the other end is 33.1 cm. What is the length of the needle?
Ans: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
6.Write
the similarities and differences between the motion of a bicycle and a ceiling
fan that has been switched on.
Ans: SIMILARITIES: a) Both the
ceiling fan and the wheels of a bicycle show cirular motion.
b) Both are fixed at point
DIFFERENCES
a) A bicycle shows rectilinear motion while a ceiling fan does not.
7.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: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.
8.Give two example of periodic motion Two examples of periodic motion
Ans: a) Motion of a pendulum clock
b) Motion of a swing
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