Physics Questions

Q:

Resistance of human body in dry condition

A) 10 ohm B) 1000 ohm
C) 10000 ohm D) 100000 ohm
 
Answer & Explanation Answer: D) 100000 ohm

Explanation:

Under dry conditions, the resistance offered by the human body may be as high as 100,000(10^5) Ohms.

 

Depending on the person, a rough value for the internal resistance of the human body is 300-1,000 Ohms. The skin's resistance is much lower if it is wet or burnt/blistered.



There are a lot of factors involved and not every person has the same electrical resistance. For instance, men tend to have lower resistance than women.

Within the body, the tissues with the greatest resistance are bone and fat - nerves and muscle have the least resistance.

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6 6787
Q:

Which resource is both renewable and inexpensive?

A) Sunlight B) Coal
C) Gold D) Minerals
 
Answer & Explanation Answer: A) Sunlight

Explanation:

A resource is a source or supply from which a benefit is produced. Resources can be broadly classified upon their availability they are renewable and non renewable resources.

 

Renewable Resources :: A resource that can be replenished after use are known as Renewable resources.

Examples :: Sunlight, Water, biomass,...

 

Non renewable Resources :: A resource that, once used, is no longer available are known as Non renewable Resources. 

Example :: Coal, fossil fuels, natural gas,...

 

Sunlight is the both renewable and inexpensive resource from the given options.

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2 6760
Q:

Why does'nt the hydrogen atom emit X-rays?

A) It is very small in size B) It has only one electron
C) Its energy levels are very close to each other D) it is highly electropositive
 
Answer & Explanation Answer: C) Its energy levels are very close to each other

Explanation:

For an atom to emit X-rays it should have difference in energy levels

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9 6751
Q:

Light year is a unit of

A) time B) speed of light
C) distance D) mass
 
Answer & Explanation Answer: C) distance

Explanation:
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10 6744
Q:

Water has maximum density at............

A) 0 C B) -15 C
C) 4 C D) 15 C
 
Answer & Explanation Answer: C) 4 C

Explanation:
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11 6744
Q:

On which day ' National Science Day ' is celebrated in India ?

A) February 23 B) February 25
C) February 26 D) February 28
 
Answer & Explanation Answer: D) February 28

Explanation:

National Science Day is celebrated in India on 28 February each year to mark the discovery of the Raman effect by Indian physicist Sir Chandrashekhara Venkata Raman on 28 February 1928.

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Q:

A tennis ball machine serves a ball vertically into the air from a height of 2 feet, with an initial speed of 110 feet per second. After how many seconds does the ball attain its maximum height?

A) 2.87 sec B) 3.44 sec
C) 4.65 sec D) 5.41 sec
 
Answer & Explanation Answer: B) 3.44 sec

Explanation:

It is launched vertically with an initial speed of 110 ft/sec.

It will reach maximum height when the speed drops to 0.

Vo=110 feet per second 

ho=2 feet 

So, h(t) = -16t^2 +110t +2 

Take the derivative: h'(t) = 110 -32t 

The maximum height will be at the inflection when the derivative crosses the x-axis, then h'(t)=0. 

So, set h'(t)=0 and solve for t: 

0 = 110 -32t 

-110 = -32t 

t=3.4375 

t=3.44 seconds.

 

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Q:

When a steel ball is placed on the surface of mercury, it does not sink because

A) of the surface tension of mercury B) mercury is a semisolid
C) of the high viscosity of mercury D) the density of mercury is greater than that of steel
 
Answer & Explanation Answer: D) the density of mercury is greater than that of steel

Explanation:

A solid sinks in a liquid if its density is greater than that of the liquid. if less, it floats

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8 6590