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Dear students, prepare for physics class 9th chapter 5 long questions. These important long questions are carefully added to get you best preparation for your 9th class physics ch. 5 exams.
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Our database contains a total of 0 questions for physics Short Questions. You’ll prepare using this huge databank.

Question: 1
Q no: 5 (A) What ismeant by the force of gravitation? Also explain the law of gravitation.
Answer: 1
1-15
<gwmw class="ginger-module-highlighter-mistake-type-1" id="gwmw-15858990725905926268240">everybody</gwmw> in the universeattracts every other body with a force which is directly proportional to the product of their masses and inversely proportional to the square of the distance between their <gwmw class="ginger-module-highlighter-mistake-type-1" id="gwmw-15858990725908631312997">centres</gwmw>.<div><br></div><div>According to the law of gravitation the gravitationalforce of attraction F with which the two masses m1 and m2 separated by a distance `d' attract each other is given by:</div><div> F x m1m2</div><div> F x 1/d²</div><div> F x m1m2/d²</div><div> F=G m1m2/d²</div>
Question: 2
Q no(B) Define satellites. Find the orbital velocity of on artificial satellites.
Answer: 2
2-15
Satellite:<div> An object that revolves around a planet is called <gwmw class="ginger-module-highlighter-mistake-type-3" id="gwmw-15858995013099199327989">satellite</gwmw><gwmw class="ginger-module-highlighter-mistake-type-6" id="gwmw-15858995013093883914005"> .</gwmw> The moon revolves around the earth as moon is a natural satellite of the earth.</div><div>Scientists have sent many objects into space Some of these objects revolve around the earth. These are called artificial<gwmw class="ginger-module-highlighter-mistake-type-1" id="gwmw-15858996262477315033213">satalites</gwmw>. Most of the artificial <gwmw class="ginger-module-highlighter-mistake-type-1" id="gwmw-15858996658100863299033">satallite</gwmw> orbiting around the Earth <gwmw class="ginger-module-highlighter-mistake-type-3" id="gwmw-15858997685528902036023">are used</gwmw>for communication purposes<gwmw class="ginger-module-highlighter-mistake-type-6" id="gwmw-15858997685520226719303"> .</gwmw>Artificial satellites carry instruments or passengers to perform experiments in space.</div><div><gwmw class="ginger-module-highlighter-mistake-type-3" id="gwmw-15858998469108475396261">Large number</gwmw> of artificial satellites have been launched in different orbits around the Earth.</div>
Question: 3
Q no: 6 (A) State Law of gravitation and derived the equation.
Answer: 3
3-15
Everybody in the universe attracts every other body with a force which is directly proportional to the product of their masses and inversely proportional to the square of the distance between their <gwmw class="ginger-module-highlighter-mistake-type-1" id="gwmw-15859002434476530837219">centres</gwmw>.<div> F x m1m2<br><div> F x 1/d²</div></div><div> F x m1m2/d²</div><div> F= Gm1m2/d²</div>
Question: 4
Q no: 6 (B) Calculate the value of g at a height of 3600 km above the surface of the Earth.
Answer: 4
4-15
Solution:<div> <gwmw class="ginger-module-highlighter-mistake-type-1" id="gwmw-15859069169768031063578">g</gwmw><sub>n</sub> =?</div><div> h = 3600km = 3600 x 1000m</div><div> R = 6400 x 10³ m</div><div> G = 6.673 x 10-¹¹ Nm²kg-²</div><div>Me = 6x 10<sup>24</sup> <gwmw class="ginger-module-highlighter-mistake-type-1" id="gwmw-15859071038786635577622">kg</gwmw></div><div> <gwmw class="ginger-module-highlighter-mistake-type-1" id="gwmw-15859071131046995375761">g</gwmw> = GMe/R²</div><div>g<sub>n</sub> = Gme/(R+h<gwmw class="ginger-module-highlighter-mistake-type-6" id="gwmw-15859071740145567494348">)</gwmw>²</div><div>6.673 x10-¹¹ x 6 x 10<sup>24</sup>/6400 x10³ + 3600 x10³</div><div> <gwmw class="ginger-module-highlighter-mistake-type-1" id="gwmw-15859074148828212774533">g</gwmw><sub>n</sub> = 4ms-²</div>
Question: 5
Q no 7 (A) Explain the motion of Artificial satellites.
Answer: 5
5-15
A satellite requires <gwmw class="ginger-module-highlighter-mistake-type-3" id="gwmw-15859076056612834907422">centripetal force</gwmw> of attraction between the <gwmw class="ginger-module-highlighter-mistake-type-1" id="gwmw-15859075744804198534486">salellite</gwmw> and the Earth provides the necessary centripetal force.<div>Consider a satellite of mass <span style="">revolving round the earth at an altitude h in <gwmw class="ginger-module-highlighter-mistake-type-3" id="gwmw-15859077092540710112286">a</gwmw> orbit of radian to with orbital velocity Vo The necessary centripetal force required is given by <gwmw class="ginger-module-highlighter-mistake-type-3" id="gwmw-15859077092540473552738">equation</gwmw></span></div><div> <gwmw class="ginger-module-highlighter-mistake-type-1" id="gwmw-15859077256236985562486">fc</gwmw> = mv²o/r<sub>o</sub></div><div> <gwmw class="ginger-module-highlighter-mistake-type-1" id="gwmw-15859078363217356085889">Fc</gwmw> = w<sup>'</sup> = mg<sub>n</sub></div><div> <gwmw class="ginger-module-highlighter-mistake-type-1" id="gwmw-15859078500556410727230">mg<sub>h</sub></gwmw>mv²o/r<sub>o</sub></div><div> V<sub>o</sub><sup>2</sup>= g<sub>h</sub> <gwmw class="ginger-module-highlighter-mistake-type-1" id="gwmw-15859079756821386053297">ro</gwmw> </div><div> <gwmw class="ginger-module-highlighter-mistake-type-1" id="gwmw-15859080130759357241101">vo</gwmw>= √g<sub>h</sub><gwmw class="ginger-module-highlighter-mistake-type-1" id="gwmw-15859080243130936192902">ro</gwmw></div><div> V<sub>o</sub>= √g<sub>n</sub><gwmw class="ginger-module-highlighter-mistake-type-6" id="gwmw-15859081718831356615452">(</gwmw>R+h)</div><div> Equation <gwmw class="ginger-module-highlighter-mistake-type-6" id="gwmw-15859091887417654681239">( </gwmw>5.10) gives the <gwmw class="ginger-module-highlighter-mistake-type-6" id="gwmw-15859091887414523965246">velocity which</gwmw> a satellite must possess when launched <gwmw class="ginger-module-highlighter-mistake-type-3" id="gwmw-15859091887412437587443">in</gwmw> an orbit of radius r<sub>o</sub>=9R+h) around the Earth</div><div> R+h= R</div><div> <gwmw class="ginger-module-highlighter-mistake-type-1" id="gwmw-15859092488636861374142">g</gwmw><sub>n</sub> = g</div><div> <gwmw class="ginger-module-highlighter-mistake-type-1" id="gwmw-15859092794775944588353">v</gwmw><sub>o</sub>=√gR</div><div> A satellite revolving around very close to the Earth has speed V<sub>o</sub> <gwmw class="ginger-module-highlighter-mistake-type-1" id="gwmw-15859094098962578921408">nearly</gwmw> 8kms-¹ or 29000 <gwmw class="ginger-module-highlighter-mistake-type-1" id="gwmw-15859094098969250226294">kmh</gwmw>-¹</div>
Question: 6
Q no: (B) A polar satellite is launched at 850 km above earth. Find its orbital speed.
Answer: 6
6-15
Solution:<div> Height= 850 km</div><div> = 850 x 1000m</div><div> 850000m = 8.5 x 10<sup>5</sup>m</div><div><gwmw class="ginger-module-highlighter-mistake-type-1" id="gwmw-15859096291363169920870">orbital</gwmw> speed = v=?</div><div>V=√GMe/(R+h)</div><div> =√6<gwmw class="ginger-module-highlighter-mistake-type-6" id="gwmw-15859096990784282521801">.</gwmw>673 x 10-¹¹ x 6 x 10<sup>24</sup>/(6.4 x 10<sup>6</sup> + 8.5 x 10<sup>5</sup> )</div><div> = 743.13 ms-¹</div>
Question: 7
Q no: (B) A polar satellite is launched at 850 km above earth. Find its orbital speed.
Answer: 7
7-15
Solution:<div> Height= 850 km</div><div> = 850 x 1000m</div><div> 850000m = 8.5 x 10<sup>5</sup>m</div><div><gwmw class="ginger-module-highlighter-mistake-type-1" id="gwmw-15859096291363169920870">orbital</gwmw> speed = v=?</div><div>V=√GMe/(R+h)</div><div> =√6<gwmw class="ginger-module-highlighter-mistake-type-6" id="gwmw-15859096990784282521801">.</gwmw>673 x 10-¹¹ x 6 x 10<sup>24</sup>/(6.4 x 10<sup>6</sup> + 8.5 x 10<sup>5</sup> )</div><div> = 743.13 ms-¹</div>
Question: 8
How gravitation is discovered. what is the force of gravitation
Answer: 8
8-15
The first man who came up with the idea of gravity was Isaac newton. It was an evening of 1665 when he was trying to solve the mystery why planets revolve around the sun. Suddenly an apple fell from the tree under which he was sitting. The idea of gravity flashed in his mind. he discovered not only the cause of falling apple but also the cause that makes the planet to revolve around the sun and the moon around the earth.<div>Force of gravitation: force due to which every body of the universe attracts every other body is called force of gravitation.</div>
Question: 9
State and explain Newtons law of gravitation. Also derive its equation
Answer: 9
9-15
Law of gravitation: Every object in the universe attracts every other object with a force which is directly proportional to the product of their masses and inversely proportional to the square of the distance between their centers.
Question: 10
How will you relate law of gravitation and Newtons third law of motion
Answer: 10
10-15
in law of gravitation it is to be noted that mass m1 attracts m2 towards it with a force F while mass m2 attract m1 towards it with a force of the same magnitude F but in opposite direction. If the force acting on m1 is considered as action then the force acting on m2 will be the reaction . We can say that the action and reaction due to force of gravitation are equal in magnitude but opposite in direction. This is in consistent with newtons third law of motion which states , to every action there is always an equal but opposite reaction
Question: 11
State and explain gravitational field
Answer: 11
11-15
Gravitational pull of earth acting on the body whether the body is in contact with earth or not is called the field force and the are for this force around the earth is called gravitational field
Question: 12
Determine the mass of earth using Newtons law of gravitation
Answer: 12
12-15
Mass of earth: the mass of earth can be calculated by using Newtons law of gravitationExplanation; consider a body of mass m is placed on the surface of the earth. The distance between the center of the body and the earth is R which is equal to radius of the earth. The mass of earth is Me.We know that the force with which the earth attracts a body on its surface towards its center is equal to the weight of the body
Question: 13
What is the effect of the following on the gravitational acceleration<div><ol><li>Mass of the freely falling body</li><li>Distance of the freely falling body from the center of the earth,(I&gt;E&gt; variation of "g" with altitude0 OR explain the variation in value of 'g' with altitude</li></ol></div>
Answer: 13
13-15
We know that<div>g= GM<sub>e</sub>/R<sup>2</sup></div><div><sup>where Me is mass of earth. Hence this equation does not include the mass of the freely fallingbody. The value of g does not depend on the mass of the body. All bodies either lighter or heavier fall freely with the same gravitationalacceleration. Thus mass has no effect on g</sup></div>
Question: 14
What do you mean by artificial satellite
Answer: 14
14-15
Satellite: an object that revolves around a planet is called a satellite<div>Natural satellite: the moon revolves around the earth so moon is a natural satellite of the earth</div><div>Artificial; scientists have sent many objects into space. Some of these objects revolve around the earth. These are called artificial satellites.</div>
Question: 15
Describe the motion of artificial satellite and derive the formula for the orbital speed of the artificial satellite
Answer: 15
15-15
Artificial satellite: Artificial satellites are launched for space research and telecommunication. With their help, we are able to enjoy live coverage of cricket matches, Olympic games and many other programs directly on our television sets.<div>Artificial satellites keep on revolving around the earth in different geo stationary satellite orbits with uniform speed due to gravitational force</div>