NCERT Class VII Science Solutions: Chapter 13-Motion and Time Part 4

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Question 15:

A spaceship travels 36,000 km in one hour. Express its speed in km/s.

Answer:

Image of formula of time speed and distance.

Formula of Time Speed and Distance

Image of formula of time speed and distance.

Question 16:

Starting from A, Paheli moves along a rectangular path ABCD as shown in Figure. She takes 2 minutes to travel each side. Plot a distance-time graph and explain whether the motion is uniform or non-uniform.

As showing in images is a rectangular

Rectangular

As showing in images is a rectangular

Answer:

Since the distance covered per unit time for the entire distance covered is not the same, the motion is non-uniform.

As showing in images is a distance-time graph of the motion is non-uniform

Distance-Time Graph of the Motion is Non-Uniform

As showing in images is a distance-time graph of the motion is non-uniform

Question 17:

Plot a distance-time graph of the tip of the second hand of a clock by selecting 4 points on respectively. The circumference of the circle traced by the second hand is .

Answer:

Time-Distance Graph
time-distance graph

Time (s)

x

15

30

45

60

Distance (cm)

y

16

32

48

64

As showing in images is a distance-time graph of the state.

Distance-Time Graph of the State.

As showing in images is a distance-time graph of the state.