Physics Questions

Q:

The velocity required to place a vehicle in orbit round the moon is _______ that required to place it in orbit round the earth 

A) less than B) Greater than
C) equal to D) greater than or equal to
 
Answer & Explanation Answer: A) less than

Explanation:

This orbital velocity at the moon is less because orbital velocity = rg

 

where 'r ' is the orbital radius. i.e the distance of the body from the center of the earth and 'g' is the acceleration due to gravity on the body in question. In the case of the moon, both r and g are less than in the case of the earth.

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Q:

The size of gear is usually specified by

A) pitch circle diameter B) diametral pitch
C) pressure angle D) circular pitch
 
Answer & Explanation Answer: A) pitch circle diameter

Explanation:

The size of gear is usually specified by pitch circle diameter.

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Q:

Echolocation is an adaptation bats use to

A) locate flowering plants B) hunt insects in flight
C) find warm places for hibernation D) All of the above
 
Answer & Explanation Answer: D) All of the above

Explanation:

Echolocation is an adaptation bats use to hunt insects in flight, locate flowering plants and find warm places for hibernation.

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Q:

A man stands on the pan of a balance holding a fish in his right hand and bucket of water in his left hand. If he transfers the fish into the bucket, the total weight on the pan 

A) increases B) decreases
C) remains the same D) first increases and then decreases
 
Answer & Explanation Answer: C) remains the same

Explanation:

Before transferring the fish, the position is the man with the fish and the bucket of water. After transferring the position is: the man without the fish, but the fish inside the water in the bucket. Thus to know  whether there is any change in weight, it is enough to consider whether there is any change in weight when the fish in air is transferred into the water. The answer is there is no change as when in water though it loses weight due to upthrust of water on it, the level of water increases and exerts an equal force at the bottom.So, (c) is correct.

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Q:

When a piece of pure silicon is doped with aluminium, then

A) the conductivity of the doped silicon piece will remain the same B) the doped silicon piece will become n-type
C) the doped silicon piece will become p-type D) the resistivity of the doped silicon piece will increase
 
Answer & Explanation Answer: C) the doped silicon piece will become p-type

Explanation:

p type of semiconductor is obtained when Silicon is doped with a trivalent impurity like Aluminium. Aluminium is a p-type dopant, which means that when a semiconductor i.e. silicon is doped with aluminium, it creates a hole (positively charged carrier) by accepting an electron from the silicon atom. Electrical conductivity of semiconductors increasesand resistivity remains the same

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Q:

A man stands on the pan of a balance holding a fish in his right hand and bucket of water in his left hand. If he transfers the fish into the bucket, the total weight on the pan

A) increases B) decreases
C) remains the same D) first increases and then decreases
 
Answer & Explanation Answer: C) remains the same

Explanation:

Before transferring the fish, the position is the man with the fish and the bucket of water. After transferring the position is : the man without the fish, but the fish inside the water in the bucket. Thus to know whether there is any change in weight, it is enough to consider whether there is any change in weight when the fish in air is transferred into the water. The answer is there is no change as when in water though it loses weight due to upthrust of water on it, the level of water increases and exerts an equal force at the bottom

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Q:

If the speed of an object moving along a straight line keeps changing, its motion is said to be _________.

A) Uniform B) Periodic
C) Circular D) Non-uniform
 
Answer & Explanation Answer: D) Non-uniform

Explanation:
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Q:

Which part of the flame is the hottest?

A) Blue Zone B) Luminous Zone
C) Dark Zone D) Non - Luminous Zone
 
Answer & Explanation Answer: A) Blue Zone

Explanation:

Blue Zone is the hottest part of the flame that is where the flame has the most Oxygen and you are getting complete combustion. It is about 1400 degrees Centigrades. The Reddish part (Non - Luminous Zone) is the coolest part, about 800 deg C.

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