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Q:

A man stands in a lift which accelerates upwards. The resultant reaction force on the floor of the lift is 

A) greater than the weight of the man B) less than the weight of the man
C) Same as the weight of the man D) Zero

Answer:   A) greater than the weight of the man



Explanation:

The weight of the man mg is acting on the floor. As the lift is moving up with an acceleration, say a, the man too in it is having this acceleration. The force producing this acceleration is ma. By Newton's third law, this force will have an equal reaction pressing the floor equal to ma. Therefore the total resultant reaction on the floor is mg+ma = m(g+a) which is mg, the weight of the man. So (a) is correct.

Subject: Physics
Q:

Light travels fastest in

A) Air B) Water
C) Glass D) Diamond
 
Answer & Explanation Answer: A) Air

Explanation:

Light travels fastest in Vacuum. The fastest thing in the whole universe is the speed of light in a vacuum like outer space. It is about 2.99 x 108 m/s. 

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Q:

How many bottles of water is a gallon?

A) 16 B) 8
C) 4 D) 2
 
Answer & Explanation Answer: B) 8

Explanation:

The easiest way would measure it through half a liter water bottle. There are approximately 16.9 ounces(oz) of water in a 500ml water bottle.

 

Gallon is an imperial customary volume unit for the U.S.

 

As we have previously mentioned, the 16.9oz bottle is also known as 500ml in the metric system. According to U.S. standard, 1 gallon stands for 128 fluid oz.

 

Hence, Number of bottles in 1 gallon = 128/16.9 = 7.57 =~ 8.

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Q:

Sound travels fastest in

A) Vacuum B) Air
C) Glass D) Water
 
Answer & Explanation Answer: C) Glass

Explanation:

Sound is a mechanical vibration and needs a medium for propagation. The higher the density of the medium, the faster the sound travels. So, sound cannot travel through vacuum.

 

As the sound travels faster in solids than liquids and gases, sound travels faster in the glass than Air and water.

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Q:

In which layer is the pressure the highest?

A) Ionosphere B) Stratosphere
C) Troposphere D) Inner core
 
Answer & Explanation Answer: D) Inner core

Explanation:

"Pressure" is the ratio of mass to area. So, for any given area, the one with more mass pressing on it will experience a higher pressure.

 

As you go more deeply into the atmosphere OR earth itself, you are putting more and more mass over you. For the same unit area therefore, the pressure, (mass/area) increases.

 

Hence, the lowest layer will always have the highest pressure i.e, inner core.

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Q:

A periscope works by the principle of

A) Total internal reflection B) Refraction
C) Diffraction D) Reflection & Refraction
 
Answer & Explanation Answer: A) Total internal reflection

Explanation:

A periscope is an optical instrument that uses a system of prisms, lenses, or mirrors to reflect images through a tube.

 

 per11526634345.jpg image

 

Light from a distant object strikes the top mirror and is then reflected at an angle of 90 degrees down the periscope tube. At the bottom of the periscope, the light strikes another mirror and is then reflected into the viewer’s eye.

 

Hence, A periscope works by the principle of Total internal reflection.

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Q:

Sound following a flash of lightning is called

A) Stoning B) Bolting
C) Thunder D) Cloud clash
 
Answer & Explanation Answer: C) Thunder

Explanation:

The Sound Following the flash of lighting is because of Thunder.

 

Lightning is seen earlier than thunder because light travels much faster than sound.

 

The roar of thunder is the result of a shock wave produced when lightning super-heats the air through which it passes, causing that air to expand very rapidly. This rapid expansion of air creates a shock wave that travels outward at close to the speed of sound.

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Q:

What is needed for steering control on a PWC?

Answer

PWC refers to Personal Water Crafts.


To control steering on a PWC, the most needed requirement is to have power in which will allows the one using it to control the engine for it to stop or for it to move. Without power, the person using it could be out of balance or fail to start the engine. This is the basic requirement because even though it is shut off or the engine is off, the PWC is still on and it could still move without proper knowledge of the engine.

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Q:

Which of the following is the largest unit of information?

A) 1 TB B) 1 GB
C) 1 MB D) 1 KB
 
Answer & Explanation Answer: A) 1 TB

Explanation:

1 TB  >  1 GB  >  1 MB  >  1 KB

 

1 Tb (Tera Byte) = 1024 GB

1 GB (Giga Byte) = 1024 MB

1 MB (Mega Byte) = 1024 KB

1 KB (Kilo Byte) = 1024 Bytes

1 Byte = 8 Bit

 

Hence, largest unit of information is TB (Tera Byte) and smallest unit of information is Bit.

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