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Mechanics

219 MCQ questions with answers and explanations · page 6 of 9

Q126. What is the approximate height of an orbiting satellite from the Earth's surface?

  1. A36,000km
  2. B42,000km
  3. C30,000km
  4. DNone of these
Show answer & explanation

Answer: A) 36,000km

Q127. A tennis ball bounces higher on a hill than on a plain because-

  1. AThe air pressure is relatively low in the mountains.
  2. BThe ball becomes lighter on the mountains
  3. CThe acceleration due to gravity of the Earth decreases in the mountains.
  4. Dnone of the above
Show answer & explanation

Answer: C) The acceleration due to gravity of the Earth decreases in the mountains.

Q128. If the gravitational force of the Earth suddenly disappears, which of the following consequences will be correct?

  1. AThe weight of the object will become zero, but the mass will remain the same.
  2. BThe mass of the object will become zero, but the weight will remain the same.
  3. CBoth the weight and mass of the object will become zero.
  4. Dthe mass of the object will increase
Show answer & explanation

Answer: A) The weight of the object will become zero, but the mass will remain the same.

Q129. What fraction of Earth's gravity is closest to the Moon's gravity?

  1. A1/5
  2. B1/4
  3. C1/6
  4. D1/8
Show answer & explanation

Answer: C) 1/6

Q130. Time Period of the Pendulum

  1. Adepends on the mass
  2. Bdepends on the length
  3. Cdepends on the temperature
  4. Ddepends on the time
Show answer & explanation

Answer: B) depends on the length

Q131. Why do pendulum clocks slow down in summer?

  1. ABecause of the long summer days
  2. Bdue to friction in the coil
  3. CThe length of the pendulum increases, which increases the time taken for a single oscillation.
  4. DThe weight of the pendulum increases in summer
Show answer & explanation

Answer: C) The length of the pendulum increases, which increases the time taken for a single oscillation.

Q132. If the length of a simple pendulum is increased by 4%, then its time period-

  1. Awill increase by 8%
  2. Bwill increase by 2%
  3. Cwill increase by 4%
  4. DNone of these
Show answer & explanation

Answer: B) will increase by 2%

Q133. If the length of the pendulum is increased four times, then the swing time of the pendulum will be-

  1. Adecreases
  2. Bis doubled
  3. Cbecomes a quarter
  4. DIt becomes four times.
Show answer & explanation

Answer: B) is doubled

Q134. When the pendulum is taken to the moon, its time period is-

  1. Awill remain the same
  2. Bwill decrease
  3. Cwill become zero
  4. Dwill increase
Show answer & explanation

Answer: D) will increase

Q135. A particle has mass and momentum p. Its kinetic energy will be-

  1. Amp
  2. Bp²m
  3. Cp²/m
  4. Dp²/2m
Show answer & explanation

Answer: D) p²/2m

Q136. Hooke's principle is related to which of the following?

  1. Aliquid pressure
  2. Belasticity
  3. Cradioactivity
  4. DNone of these
Show answer & explanation

Answer: B) elasticity

Q137. small drop of oil spreads on water because

  1. AThe viscosity of the oil is high
  2. Bwater has high viscosity
  3. COil has high surface tension
  4. Dwater has high surface tension
Show answer & explanation

Answer: C) Oil has high surface tension

Q138. The principle of cleaning surfaces with soap is based on-

  1. Aon viscosity
  2. Bon flotation
  3. Con elasticity
  4. Don surface tension
Show answer & explanation

Answer: D) on surface tension

Q139. Why does the shape of a raindrop become spherical?

  1. Aviscosity
  2. BSurface tension
  3. Celasticity
  4. Dgravity
Show answer & explanation

Answer: B) Surface tension

Q140. A liquid droplet assumes a spherical shape

  1. Adue to surface tension
  2. Bdue to viscosity
  3. Cdue to upward thrust
  4. Ddue to gravity
Show answer & explanation

Answer: A) due to surface tension

Q141. Mosquitoes are reduced when kerosene is added to stagnant water because it-

  1. Ainterferes with reproduction
  2. BHighly toxic to mosquitoes
  3. Cobstructs the breathing of larvae
  4. Drepels mosquitoes
Show answer & explanation

Answer: C) obstructs the breathing of larvae

Q142. The bristles of a shaving brush stick together when removed from water. This is because:

  1. ASurface tension
  2. Bviscosity
  3. Celasticity
  4. Dfriction
Show answer & explanation

Answer: A) Surface tension

Q143. A boy sitting in an open car traveling at a constant speed throws a ball straight up in the air. The ball falls

  1. Abehind him
  2. Bin front of him
  3. Cin his hand
  4. Dnext to him
Show answer & explanation

Answer: C) in his hand

Q144. person is at rest in the middle of a horizontal plane of perfectly smooth ice. Using which of Newton's laws can he bring himself to shore?

  1. Afirst law of motion
  2. Bsecond law of motion
  3. CThird law of motion
  4. DFirst, second and third laws of motion
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Answer: C) Third law of motion

Q145. Why do small pieces of camphor dance on the surface of water?

  1. Adue to surface tension
  2. Bdue to viscosity
  3. CThis is the property of camphor
  4. Ddue to the density of water
Show answer & explanation

Answer: A) due to surface tension

Q146. When detergent is added to pure water, the surface tension

  1. Aincreases
  2. Bhappens to
  3. Cremains unchanged
  4. Dbecomes infinite
Show answer & explanation

Answer: B) happens to

Q147. Surface tension when soap is dissolved in water

  1. Ahappens to
  2. BIt increases.
  3. Cremains unchanged
  4. DFirst it decreases and then it increases.
Show answer & explanation

Answer: A) happens to

Q148. Ventilators are installed near the ceiling of the room because-

  1. AThe warm air exhaled rises and is expelled
  2. BThey provide cross ventilation in the room.
  3. CThey provide some light in the room.
  4. DIt doesn't look good at the bottom
Show answer & explanation

Answer: A) The warm air exhaled rises and is expelled

Q149. Assertion (A) Detergents easily remove oil and dirt from dirty clothes. Reason (R) Detergents increase the surface tension of water.

  1. ABoth A and R are correct and R is the correct explanation of A.
  2. BBoth A and R are correct, but R is not the correct explanation of A
  3. CA is correct, but R is incorrect
  4. DA is wrong, but R is correct
Show answer & explanation

Answer: C) A is correct, but R is incorrect

Q150. Astronauts cannot stand upright in space because—

  1. Athere is no gravity
  2. BThe force of viscosity is very strong in the atmosphere.
  3. CThe solar wind exerts an upward force
  4. Datmospheric pressure is very low
Show answer & explanation

Answer: A) there is no gravity

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