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Q:

A boy sitting in a train moving with a uniform velocity drops a coin outside. A man standing outside the train will find the trajectory of the coin to be

A) a parabola B) a circle
C) a horizontal straight line D) a vertical straight line

Answer:   A) a parabola

Explanation:

Parabola, because when the coin is dropped at a particular point, it has the same velocity as the running train. So by Newton's first law, it continues its motion horizontally with that velocity. But then, it is also pulled down by earth's gravity continuously. In this situation its horizontal motion gives way to the parabolic motion until it reaches the ground.

Subject: Physics
Q:

The capacity of a pure capacitor is 1 farad. In D.C circuit, its effective resistance will be

A) Zero B) Infinite
C) 1 Ohm D) 1/2 Ohm
 
Answer & Explanation Answer: B) Infinite

Explanation:
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Q:

A convex mirror is used to form an image of a real object. The image

A) is diminished in size B) is erect
C) always lies between the pole and the focus D) all of the above
 
Answer & Explanation Answer: D) all of the above

Explanation:
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Q:

The quality of sound produced by an instrument depends on the

A) Frequency B) Intensity
C) Number of overtones D) None of these
 
Answer & Explanation Answer: C) Number of overtones

Explanation:
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Q:

In the electrical circuit of a house, the fuse acts as

A) a load B) a thermopile
C) a safety device D) a step down device
 
Answer & Explanation Answer: C) a safety device

Explanation:
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Q:

The direction of heat flow between two objects depends on

A) Their masses B) Their heat contents
C) Their temperatures D) Whether they are in solid, liquid or gaseous state
 
Answer & Explanation Answer: C) Their temperatures

Explanation:

Heat always flows from a body at higher temperature to a body at a lower temperature.

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