36
Q:

A boat loaded with rocks floats in the middle of a swimming pool. A man in the boat throws the rocks overboard. The level of water in the pool will

A) increase B) decrease
C) remains the same D) first decrease and then increase

Answer:   B) decrease



Explanation:

Let M and m grams be the mass of boat + rock in it. By law of floatation(M+m) grams of water will be displaced. This has a volume of (M+m)cc. That means the level of water in pool has risen up by (M+m)cc with the boat + rock when it is floating. If the rocks in the boat are thrown not into the pool but outside, the weight left is only M grams the weight of the boat. This will have displaced M cc of water only i.e less water than in the case of loaded boat. But if the rocks are put in the water in the pool and not outside, then the water in the pool will rise not only by M cc on account of empty boat but also by a volume of the stone put into it. This volume will be mdwhere m is the mass of rock and d density of rock.

Now md is  < m. Thus the total rise will be M+mdwhich is < M + m.

Subject: Physics
Exam Prep: AIEEE , CAT
Job Role: Analyst
Q:

What is the noise level of normal conversation?

A) About 60 dB B) About 70 dB
C) About 80 dB D) About 90 dB
 
Answer & Explanation Answer: A) About 60 dB

Explanation:
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3 299
Q:

As an object falls freely its ___________________.

 

A) kinetic energy gets converted into potential energy B) potential energy gets converted into kinetic energy
C) momentum gets converted into gravitational force D) gravitational force gets converted into momentum
 
Answer & Explanation Answer: B) potential energy gets converted into kinetic energy

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0 8916
Q:

Due to an acceleration of 1  m/s2, the velocity of a body increases from 5 m/s to 10 m/s in a certain period. Find the displacement (in m) of the body in  that period.

 

A) 125 B) 37.5
C) 62.5 D) 75
 
Answer & Explanation Answer: B) 37.5

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2 314
Q:

What is measured with the Nephometer?

 

A) volume of rainfall B) Cloud volume and speed
C) Salinity of Sea D) All options are correct.
 
Answer & Explanation Answer: B) Cloud volume and speed

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1 3594
Q:

What is the standard room temperature in Kelvin?

 

A) 98 K B) 198 K
C) 273 K D) 373 K  
 
Answer & Explanation Answer: A) 98 K

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0 2126
Q:

An object, starting from rest, moves with constant acceleration of 4 m/s2. After 8 s, its speed is

A) 16 m/s B) 8 m/s
C) 32 m/s D) 4 m/s
 
Answer & Explanation Answer: C) 32 m/s

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1 240
Q:

1 watt is equal to 1 ____________

 

A) J s-1   B) J s
C) J s-2 D) J
 
Answer & Explanation Answer: A) J s-1  

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2 3943
Q:

A body is initially moving with a velocity of 10 m/s. It undergoes an acceleration of 2 m/s2 for 5 seconds. Find the displacement (in m) of this body in these 5 seconds.

 

A)  25 B)  37.5
C)  50 D)  75
 
Answer & Explanation Answer: D)  75

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0 305