Gravitation : Physics

 

Answers are in BOLD Option name. 

Q.1.  Choose the wrong statement. The escape velocity of a body for a planet depends upon 

 A) the mass of body 

 B) the mass of the planet 

 C) the average radius of the planet 

 D) the average density of the planet 

Q.2. The acceleration due to gravity g on earth is 9.8 ms. What would the value of g fir a planet whose size is the same as that of earth but the density in twice that of earth?

 A) 19.6 ms 

 B) 9.8 ms

 C) 4.9 ms

 D) 2.45 ms 

Explanation-

Volume of earth (V) = . Therefore, density of earth is 

Now  . Since R is the same for both planets, if  is doubled, the value of g is also doubled.

Q.3. A satellite id orbiting the earth in a circular orbit of radius r. Its period of revolution varies as

 A)  

 B)   

 C)  

 D)  

Explanation-

The speed the satellite is given by

 

Therefore, its period of revolution is

 

Q.4. Critical velocity of a satellite is a....

A) Vertical velocity given to a satellite so that its orbit is circular 

B) Vertical velocity given to a satellite so that its orbit is elliptical

C) Horizontal velocity given to a satellite so that its orbit is elliptical 

D) Horizontal velocity given to a satellite so that its orbit is circular 

Explanation-

Critical velocity is the maximum velocity given to the satellite in horizontal direction so that it revolves in circular orbit around the earth

Q.5. A planet has (1/49) times the mass and (1/4) times the radius of the earth. The ratio of the accelerations due to gravity on the surface of the planet and the earth is...

A) 16:49

B) 2:7

C) 4:49

D) 4:7

Explanation-

 

Q.6. If the lift travels vertically downward with uniform velocity equal to 9.8 m/ s the reading of spring balance for a body of weight W in stationary lift is...

A) W

B) 2 W

C) W/2

D) zero

Explanation-

Motion of the lift either downward or upward with uniform velocity makes no difference in the weight. So reading of spring balance is W.

Q.7. The weight of a body on the surface of the earth is 75 kg. The same at a depth equal to one third of the radius of the earth is...

A) 25 kg 

B) 50 kg 

C) 125 kg 

D) 150 kg 

Explanation-

 

Q.8. The binding energy of a stationary body of mass m at height h from the surface of the earth of mass M and radius R is...

A) mGM/(R + h)

B) - mGM/(R + h)

C) mGM/2(R + h)

D) - mGM/2(R + h)

Explanation-

Total energy of a stationary body at height h is

       

Q.9. The weight of an object in the coal mine , sea level , at the top of the mountain are  respectively , then [Odisha JEE 2008 ]

A) 

B) 

C) 

D)  

Explanation-

Because value of g decreases when we move either in coal mine or at the top of mountain.

Q.10. The value of g decreases inside the surface of Earth because,     [ MP PET 2010 ]

A) A force of upward attraction is applied by the shell of Earth above 

B) The shell of Earth above exerts no net force

C) The distance from the center of the Earth decreases 

D) The density of the material at the Centre of the Earth is very small 

Explanation-

Intensity inside a shell is zero.

Diversity in the Living World : Biology

• click here (For More Questions based on Biology )
• Answers are in BOLD Option name.

Q.1.  In-vitro , metabolic reactions means 

 A) reactions occurs in laboratory conditions 

 B) reactions occurs in cell free system 

 C) both (a) and (b) 

 D) none of these

Q.2. The pasted specimens on herbarium are sprayed with 

A) Formaline 

B) 0.1 solution of HgCI

​C) 1% glacial acetic acid 

D)  Alcohol 

Q.3. Which of the following characters is not associated with yeast?

​A) They form pseudo mycelium

B) They possess cleistothecium as fruiting body

C) Birth and bud scar are present on opposite sides of a cell of budding yeast

D) They are saprobic and facultative aerobes

Q.4.  Study the four statements (I-IV) given below and select the two correct ones out of them : (NEET 2016, phase II)     

I. Definition of biological species was given by Ernst Mayr.

II. Photoperiod does not affect reproduction in plants.

III. Binomial nomenclature system was given by RH Whittaker

IV. In unicellular organism reproduction is synonymous with growth.

    The two correct statements are right.

A)  II and III   

B)  III and IV 

C)  I and IV) 

D) I and II

Q.5.  The living organisms can be un-exceptionally distinguished from the non-living things on the basis of their ability for       [CBSE AIPMT 2007]

A) responsiveness to touch

B) interaction with the environment and progressive to evolution

C) reproduction

D) growth and movement

Q.6.  There is no life on moon due to the  absence of      ​[CBSE AIPMT 2002]

A) O 2

B) water

C) light

D) temperature

Q.7. Adaptations shown by birds are

A) shape of beaks

B) type of claws and pneumatic bones

C) modification of fore limbs into wings

D) all of the above

Q.8. Find the odd structure in the life cycle of smile molds with respect to ploidy level

​A) Plasmodium

B) Macro cyst

C) Microcyst 

D) Cyst and Sclerotium

Q.9. Which one of the following is called " fallen stars"?

​A) microcystic

B) Microsites

C) Nostoc

D) Spirulina

Q.10.  Viroid's differ from viruses in having   [NEET 2017]

A) DNA molecules with protein coat

B)DNA molecules without protein coat

C) RNA molecules with protein coat

D) RNA molecules without protein coat

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