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Chapter Review:

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• The distance covered by an object in a unit time as the speed of the object.
• If the speed of an object moving along a straight line keeps changing, its motion is said to be non-uniform.
• An object moving along a straight line with a constant speed is said to be in uniform motion.
• The time taken by the pendulum to complete one oscillation is called its time period.
• The basic unit of time is a second.
• The speedometer of a car measure Speed. 
• The odometer of a car measure Distance.
• The speed is the total distance covered divided by the total time taken is called average speed. 
• The time between one sunrise and the next was called a day.
• A month was measured from one new moon to the next.
• A year was fixed as the time taken by the earth to complete one revolution of the sun.
• The metallic ball is called the bob of the pendulum.
• The to and fro motion of a simple pendulum is an example of a periodic or an oscillatory
  motion.
• The smallest time interval that can be measured with commonly available clocks and watches is one second.

Exercise : 

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Que1. Classify the following as motion along a straight line, circular or oscillatory motion:

(i) Motion of your hands while running.

(ii) Motion of a horse pulling a cart on a straight road.

(iii) Motion of a child in a merry-go-round.

(iv) Motion of a child on a see-saw.

(v) Motion of the hammer of an electric bell.

(vi) Motion of a train on a straight bridge.

Answer: 

straight line motion : (ii), (vi) 

circular motion : (iii), (iv)

oscillary motion : (i), (v) 

2. Which of the following are not correct?

(i) The basic unit of time is second.

(ii) Every object moves with a constant speed.

(iii) Distances between two cities are measured in kilometres.

(iv) The time period of a given pendulum is not constant.

(v) The speed of a train is expressed in m/h.

Answer : 

(i) True 

(ii) False 

(iii) True

(iv) False

(v) False 

3. A simple pendulum takes 32 s to complete 20 oscillations. What is the time period of the pendulum?

4. The distance between two stations is 240 km. A train takes 4 hours to cover this distance. Calculate the speed of the train.

5. The odometer of a car reads 57321.0 km when the clock shows the time 08:30 AM. What is the distance moved by the car, if at 08:50 AM, the odometer reading has changed to 57336.0 km? Calculate the speed of the car in km/min during this time. Express the speed in km/h also.

6. Salma takes 15 minutes from her house to reach her school on a bicycle. If the bicycle has a speed of 2 m/s, calculate the distance between her house and the school.

7. Show the shape of the distance-time graph for the motion in the following cases:

(i) A car moving with a constant speed.

(ii) A car parked on a side road.

8. Which of the following relations is correct?

(i) Speed = Distance Time

(ii) Speed = Distance Time

(iii) Speed = Time Distance

(iv) Speed = 1 Distance

 9. The basic unit of speed is:

(i) km/min

(ii) m/min

(iii) km/h

(iv) m/s

10. A car moves with a speed of 40 km/h for 15 minutes and then with a speed of 60 km/h for the next 15 minutes. The total distance covered by the car is: (i) 100 km (ii) 25 km (iii) 15 km (iv) 10 km

11. Suppose the two photographs, shown in Fig. 13.1 and Fig. 13.2, had been taken at an interval of 10 seconds. If a distance of 100 metres is shown by 1 cm in these photographs, calculate the speed of the blue car.

12. Fig. 13.15 shows the distance-ti

me graph for the motion of two vehicles A and B. Which one of them is moving faster? (i) (ii) Fig. 13.15 Fig. 13.15 Distance-time graph for the motion of two cars

13. Which of the following distance-time graphs shows a truck moving with speed which is not constant? 

Additional Questions With solution: 

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Ques: – Define speed.

Ans: – We call the distance covered by an object in a unit time as the speed of the object.

Ques: – What is non-uniform motion?

Ans: – If the speed of an object moving along a straight line keeps changing, its motion is said to be non-uniform.

Ques: – What is uniform motion?

Ans: –  An object moving along a straight line with a constant speed is said to be in uniform motion.

Ques: – Define time period?

Ans: – The time taken by the pendulum to complete one oscillation is called its time period.

Ques: – What is the bob of the pendulum?

Ans: – The metallic ball is called the bob of the pendulum.

Ques: – What is periodic or an oscillatory motion?

Ans: – The to and fro motion of a simple pendulum is an example of a periodic or an oscillatory motion.

Ques: – Name the basic unit of time.

Ans: – The basic unit of time is a second.

Ques: – What tells the speedometer of a car?

Ans: – Speed.

Ques: – What tells the odometer of a car?

Ans:– Distance.

Ques: – What is odometer?

Ans: – Another meter that measures the distance moved by the vehicle. This meter is known as an odometer.

Ques: – A simple pendulum takes 32 s to complete 20 oscillations. What is the time period of the pendulum?

Ans: - 

Ques :– The distance between two stations is 240 km. A train takes 4 hours to cover this distance. Calculate the speed of the train.

Ans :–

Distance = 240 km

Taken time = 4 hours

Ques :– Salma takes 15 minutes from her house to reach her school on a bicycle. If the bicycle has a speed of 2 m/s, calculate the distance between her house and the school.

Ans :- 

Extra - Question:

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Que: Give the basic unit speed.

Ans: Metre/ second in the basic unit of speed.

Que: Mention which is the most common thing in almost all the clocks.

Ans:  The most common thing in almost all the clocks is that all of them shown periodic motion.

Que: Name they axis that represents dependent variable.

Ans: Y - axis represent the dependent variable.

Que: State how do we measure time interval by month.

Ans: Time intrval of a month is measures by one new moon to the next.

Que: Estimate that how many hours are there ina year.

Ans: in a year, we have 365 days and 1 day = 24h

So, for 365 days