NCERT Class 9 Science Solutions: Chapter 8 – Motion Part 8

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Question 8:

Q. The speed-time graph for a car is shown is fig.8.12

Speed Time Graph of Car

(a)Find out how far the car travels in the first 4 seconds. Shade the area on the graph that represents the distance travelled by the car during the period.

Answer:

Speed Time Graph of Car Part (A)

The shaded area which is equal to represented the distance travelled by the car in the first 4 s.

(b) Which part of the graph represents uniform motion of the car?

Answer:

Speed Time Graph of Car Part (B)

The part of the graph in red color between time 6 s to 10 s represents uniform motion of the car.

Q 8 Image Showing Speed Time Graph.

Q 8 Image Showing Speed Time Graph

Question 9

State which of the following situations are possible and give an example for each of these:

Q. (a) an object with a constant acceleration but with zero velocity.

Answer:

Possible

When a ball is thrown up at maximum height, it has zero velocity, although it will have constant acceleration due to gravity, which is equal to 9.8

Q. (b) an object moving in a certain direction with an acceleration in the perpendicular direction.

Answer:

Possible

When a car is moving in a circular track, its acceleration is perpendicular to its direction.