Chapter  :  Motion and Measurement of Distances

Q1. Name few means of  transport available in ancient times  before the invention of wheel.
Ans 1. Boats and domestic  animals.

Q2. Which invention  made  a great change in modes of transport
Ans2. invention of the  wheel.

Q3. Name some commonly  used  units of measurements in  ancient times.
Ans.  the length of a foot,  the width of a finger, and the distance of  a step, a handspan and a cubit.

Q4.  In taking measurement  of a length using a scale, what precautions  should we take?
Ans.  we need to take  care of the following:
1.   Place  the scale in contact with the object along  its length as shown in Fig.10.7. NCERT
2.   In some  scales, the ends may be broken. You  may not be able to see the zero mark clearly (Fig.10.8 (a)].
In such cases, you should  avoid taking measurements from the  zero mark of the scale. You can use  any other full mark of the scale, say, 1.0 cm  . Then you must subtract the reading of  this mark from the reading at the other  end.
3.   Correct position of the  eye is also important for taking measurement. Your eye must be exactly  in front of the point where the measurement  is to be taken.
Q5.    How do you decide whether  an object is in motion or at rest?
Ans.   If a body changes  its position with respect to its surroundings,  it is said to be in motion, and if it does  not change its position with respect  to its surroundings, it is at rest.

Q6.    How can we decide that  how  fast or slow a motion is.
Ans.   Motion is a change  in the position of an object with time.
The change in this  position can be determined through distance  measurements. This allows us to know  how fast or slow a motion is.
The movement of a snail on  the ground, ----SLOW An aeroplane flying high up  in the air   -       Fast

Q7.   Name the S.I. unit  of length.
Ans.  Metre is the unit of  length in SI unit.

Q8.    The ball is rolling on  the ground – Name the type of motion  exhibited by it.
Ans.  the ball undergoes  a rectilinear motion as well as rotational  motion.

Q9. What do you mean  by measurement?
Ans. measurement means  the comparison of an unknown quantity  with a known quantity.

Q10. In how many parts  do we express the result of a measurement ?
Ans. The result of a measurement  is expressed in two parts.
One part is a number. The  other part is the unit of the measurement.  For example, if in Activity 1,  the length of the room is found to be  12cm. 12 is the number and cm   is the unit selected for the measurement.

Q11. When is the motion  of a body said to be rectilinear ,circular, periodic  ?
Ans.  When objects move  along a straight line,the type of motion  they possess is rectilinear motion.

When the distance of the  object from the centre  remains the same,  the type of motion It  possesses  is circular  motion.

When an object or a part  of it repeats its motion after a fixed  interval of time, the type of motion It  possesses  is  periodic motion.