Important Questions With solutions:
Q1: Define unit.
Ans: Measurement means the comparison of an unknown quantity with some known quantity. This known fixed quantity is called a unit.
Q2: What is S. I unit ?
Ans: The system of units now used is known as the International System of Units (SI units).
Q3: Write the SI unit of length.
Ans: The SI unit of length is a metre.
Q4: Write the full form of S. I Unit.
Ans: International System of Units (SI units)
Q5: What is periodic motion?
Ans: An object or a part of it repeats its motion after a fixed interval of time. This type of motion is called periodic motion.
Q6: Give three examples of periodic motion.
Ans:
(i) Motion of a pendulum,
(ii) a branch of a tree moving to and fro,
(iii) motion of a child on a swing,
Q7: What is motion?
Ans: The changing in position of an object along with time is called motion.
Q8: What is rectilinear motion?
Ans: The objects move along a straight line. This type of motion is called rectilinear motion.
Q9: What is circular motion?
Ans: When an object moves along the circular path like a stone, the distance of the stone from your hand remains the same. Such type of motion is called circular motion. Ex. –
Q10: Give two example of circular motion.
Ans: (i) The motion of a point marked on the blade of an electric fan (ii) the hands of a clock are examples of circular motion.
Q11: Which vehicle is used to travel or transport from the Earth to other planets?
Ans: spacecraft.
Q12: Name few means of transport available in ancient times before the invention of wheel.
Ans: Boats and domestic animals.
Q13: Which invention made a great change in modes of transport?
Ans: invention of the wheel.
Q14: Which invention introduced a new source of power?
Ans: The invention of steam engine introduced a new source of power.
Q15: 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.
Q16: 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.
Q17: 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, an aeroplane flying high up in the air fast
Q18: Name the S.I. unit of length.
Ans: Metre is the unit of length in SI unit.
Q19: 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.
Q20: What do you mean by measurement?
Ans: Measurement means the comparison of an unknown quantity with a known quantity.
Q21: 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.
