Ch-13 Questions 1 to 20

Chapter-13

Motion and Time

Sr NO.	QUESTION	ANSWER
1.	What are different directions of motion?	Motion could be along a straight line, it could be circular or periodic.
2.	Solution to Table 13.1	Example of motion Type of motion Motion. Along a straight line/circular/periodic Soldiers in a march past. Periodic. Bullock cart moving on a straight road. Strait line. Hands of an athlete in a race. Periodic. Pedal of a bicycle in motion. Circular. Motion of the earth around the sun. Circular Motion of a swing. Periodic. Motion of a pendulum. Periodic.
3.	Ten objects moving along a straight line.	Bicycle or a motor vehicle moving on a straight road. Movement of a bullet from a triggered gun. Water flowing from an open tap. Spitting. Beam of light from a torch. Falling of an object from an elevated floor. Movement of a nail while fixing it. Movement of root of a tree. Movement of a lift. Movement of medicine from a syringe while executing injection.
4.	How we can decide which one is faster during a given interval of time?	One who takes shortest time to cover the distance of 100 metres has the highest speed. A higher speed seems to indicate that a given distance has been covered in a shorter time, or a larger distance covered in a given time.
5.	What are different directions of motion?	Motion could be along a straight line, it could be circular or periodic.
6.	We call the distance covered by an object in a unit time as the ____ of the object.	Speed.
7.	What it mean that, a car is moving with a speed of 50 kilometeters in an hour.	When we say that a car is moving with a speed of 50 kilometres per hour, it implies that it will cover a distance of 50 kilometres in one hour.
8.	A car seldom moves with a constant speed for one hour. The how we can say that a speed of a car is a certain kilometers in one hour?	When we say that the car has a speed of 50 kilometres per hour, we usually consider only the total distance covered by it in one hour. The speed calculated here is actually the average speed of the car.
9.	What is the formula to calculate average speed of a movement?	Speed is the total distance covered divided by the total time taken.
10.	What is non-uniform motion?	If the speed of an object moving along a straight line keeps changing, its motion is said to be non-uniform.
11.	What is uniform motion?	An object moving along a straight line with a constant speed is said to be in uniform motion.
12.	In uniform motion, the average speed is the same as the ____.	Actual speed.
13.	How our elders could tell the approximate time of the day by just looking at shadows?	Our ancestors noticed that many events in nature repeat themselves after definite intervals of time.
14.	What you mean by the phrase 'a day'?	The time between one sunrise and the next was called a day.
15.	What you mean by the phrase 'a year'?	A year was fixed as the time taken by the earth to complete one revolution of the sun.
16.	What you mean by the phrase 'a year'?	A year was fixed as the time taken by the earth to complete one revolution of the sun.
17.	_____ or ______ are perhaps the most common time measuring devices.	Clocks, watches.
18.	How clocks and watches measure time?	It works with the help periodic motion.
19.	One of the most well-known example of periodic motions is ______.	A simple pendulum.
20.	What are the various parts of a pendulum?	A simple pendulum consists of a small metallic ball (bob) or a piece of stone suspended from a rigid stand by a thread