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Page No 107: - Chapter 8 Motion class 9 ncert solutions Science - SaraNextGen [2024]


Question 1:

What is the nature of the distance−time graphs for uniform and non-uniform motion of an object?

Answer:

The distance−time graph for uniform motion of an object is a straight line (as shown in the following figure).

https://img-nm.mnimgs.com/img/study_content/curr/1/9/8/120/472/Chapter%208_html_230046cf.jpg

The distance−time graph for non-uniform motion of an object is a curved line (as shown in the given figure).

https://img-nm.mnimgs.com/img/study_content/curr/1/9/8/120/472/Chapter%208_html_m200804fd.jpg

 

Question 2:

What can you say about the motion of an object whose distance−time graph is a straight line parallel to the time axis?

Answer:

When an object is at rest, its distance−time graph is a straight line parallel to the time axis.

https://img-nm.mnimgs.com/img/study_content/curr/1/9/8/120/476/Chapter%208_html_m14cbb2bc.jpg

A straight line parallel to the x-axis in a distance−-time graph indicates that with a change in time, there is no change in the position of the object. Thus, the object is at rest.

 

Question 3:

What can you say about the motion of an object if its speed−time graph is a straight line parallel to the time axis?

Answer:

Object is moving uniformly.

https://img-nm.mnimgs.com/img/study_content/curr/1/9/8/120/480/Chapter%208_html_m318a8511.jpg

A straight line parallel to the time axis in a speed−time graph indicates that with a change in time, there is no change in the speed of the object. This indicates the uniform motion of the object.

 

 

Question 4:

What is the quantity which is measured by the area occupied below the velocity−time graph?

Answer:

Distance

https://img-nm.mnimgs.com/img/study_content/curr/1/9/8/120/485/Chapter%208_html_m27aa2315.jpg

The graph shows the velocity−time graph of a uniformly moving body.

Let the velocity of the body at time (t) be v.

Area of the shaded region = length × breath

Where,

Length = t

Breath = v

Area = vt = velocity × time …(i)

We know,

Velocity = DisplacementTIme

∴ Displacement = Velocity × Time…(ii)

From equations (i) and (ii),

Area = Displacement

Hence, the area occupied below the velocity−time graph measures the displacement covered by the body.

Also Read : Page-No-109:-Chapter-8-Motion-class-9-ncert-solutions-Science

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