Mechanics

91.When an object is taken from the Earth to the Moon, then-
 
A. Weight increases
 
B. Weight decreases
 
C. There is no change in its weight
 
D. weightless
 
Option “B” is correct.
Gravity on moon is 61 of that on the earth. So, if a body is taken to moon, the moon attracts the body with a force less as compared to the attraction force by the earth. Hence the weight decreases.
92.Match List-I with List-II and select the correct answer from the code given below the Lists : List-I (Quantity) A. Electric force B. Electric charge C. Electric potential D. Electric capacitance List-II ( Unit) 1. Volt 2. Newton 3. Coulomb 4. Farad
 
A. A → 1, B → 2, C → 3, D → 4
 
B. A → 2, B → 3, C → 1, D → 4
 
C. A → 4, B → 3, C → 2, D → 1
 
D. A → 2, B → 3, C → 4, D → 1
 
Option”A” is correct
93.A satellite is moving in a circular orbit around the earth due to gravitational force. What is the effect on gravitational force and speed if the radius of orbit is reduced?
 
A. Gravitational Force increases and speed increases
 
B. Gravitational Force increases and speed decreases
 
C. Gravitational Force decreases and speed increases
 
D. Gravitational force decreases and speed decreases
 
Option”A” is correct

The gravitational force 

If radius of orbit is reduced , the value of r will decrease. Thus, the gravitational force will increase. 
Due to circular motion the centripetal force is equal to gravitational force i.e, 
From this, as F increases so velocity also increases. 

94.Automatic wrist watches get energy
 
A. Convulsively
 
B. From battery
 
C. From liquid crystal
 
D. By the various movements of our hands
 
Option”D” is correct

An automatic watch movement uses a rotor, or metal weight, to power the timepiece. The rotor will oscillate freely within the watch. Every time the wearer moves their wrist, the rotor spins. That intrinsic spinning motion is transferred into energy that winds the mainspring in the watch automatically

95.When we pull up a bucket of water from the well, we feel that the bucket
 
A. Heavy above the surface of the water
 
B. Light above the surface of the water
 
C. Has lost stability coming out of the water
 
D. Come out of the water and gain in its mass
 
Option”A” is correct
96.There is weightlessness
 
A. Zero position of gravity
 
B. When gravity decreases
 
C. In vacuum
 
D. None of the above
 
Option”A” is correct
97.Which of the following is most elastic
 
A. Rubber
 
B. Wet Soil
 
C. Steel
 
D. Plastic
 
Option”D” is correct.

  • Steel is the most elastic material.
  • If the object is elastic, the body regains its original shape when the pressure is removed.
  • Steel having the steepest linear stress-strain curve among all.
  • A stiffer material will have a higher elastic modulus.

98.An earth satellite moves continuously in its orbit due to the effect of centrifugal force which is obtained from
 
A. From the rocket engine that propels the satellite
 
B. Earth’s gravitational pull on the satellite
 
C. Gravity exerted by the sun on the satellite
 
D. Gravity exerted by the satellite on the earth
 
Option”A” is correct
99.Energy stored in the spring of a clock
 
A. Kinetic energy
 
B. Potential energy
 
C. Heat energy
 
D. Chemical energy
 
Option”A” is correct
100.The sensation of weightlessness in an orbiting spacecraft is due to
 
A. Lack of external gravity
 
B. Acceleration in orbit is equal to acceleration due to external gravity
 
C. External gravity but not inside the spacecraft
 
D. Spacecraft power outages in orbit
 
Option”A” is correct

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