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# NCERT solutions Science Class 7 chapter 13 Motion and Time

## Chapter 13 - Motion and Time

#### Pages 156 - 1567

Classify the given motion along a straight line, circular or oscillatory motion:

Motion of your hands while running.

Q 1.1 | Page 156

Classify the given motion along a straight line, circular or oscillatory motion:

Motion of a horse pulling a cart on a straight road.

Q 1.2 | Page 156

Classify the given motion along a straight line, circular or oscillatory motion:

Motion of a child in a merry-go-round.

Q 1.3 | Page 156

Classify the given motion along a straight line, circular or oscillatory motion:

Motion of a child on a see-saw.

Q 1.4 | Page 156

Classify the given motion along a straight line, circular or oscillatory motion:

Motion of the hammer of an electric bell.

Q 1.5 | Page 156

Classify the given motion along a straight line, circular or oscillatory motion:

Motion of a train on a straight bridge.

Q 1.6 | Page 156

Which of the following are not correct?

(1) The basic unit of time is second.

(2) Every object moves with a constant speed.

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

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

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

Q 2 | Page 156

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

Q 3 | Page 156

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

Q 4 | Page 156

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.

Q 5 | Page 156

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.

Q 6 | Page 156

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

A car moving with a constant speed.

Q 7.1 | Page 156

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

A car parked on a side road.

Q 7.1 | Page 1567

Which of the following relations is correct?

1) Speed = Distance × Time

2) Speed = "Distance"/"Time"

3) Speed = "Time"/"Distance"

4) Speed = 1/"Distnace x Time"

Q 8 | Page 156

The basic unit of speed is:

1) km/min

2) m/min

3) km/h

4) m/s

Q 9 | Page 157

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:

(1) 100 km

(2) 25 km

(3) 15 km

(4) 10 km

Q 10 | Page 157

Suppose the two photographs, shown in Figure 1 and Figure 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.

Figure 1 Vehicles moving in the same direction of on a road

Figure 2 Position of vehicles shown in Figure 1 after some time

Q 11 | Page 157

Figure shows the distance-time graph for the motion of two vehicles A and B. Which one of them is moving faster?

Figure: Distance-time graph for the motion of two cars

Q 12 | Page 157

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

(1)

(2)

(3)

(4)

Q 13 | Page 157

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