GATE Questions

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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Filed Under: Physics
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3 5513
Q:

A train 125 m long passes a man, running at 4 km/hr in the same direction in which the train is going, in 10 seconds. The speed of the train is:

A) 49 kmph B) 50 kmph
C) 51 kmph D) 52 kmph
 
Answer & Explanation Answer: A) 49 kmph

Explanation:

Speed of the train relative to man

= (125/10) m/sec = (25/2) m/sec.

[(25/2) x (18/5)] km/hr = 45 km/hr.

Let the speed of the train be 'x' km/hr.

Then, relative speed = (x - 4) km/hr.

x - 4 = 45 => x = 49 km/hr.

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7 5512
Q:

Which of the following is the strongest base?

A) LiCH3 B) LiF
C) LiOH D) LiNH2
 
Answer & Explanation Answer: A) LiCH3

Explanation:

The stability of the ions is determined by the energy of the lone pairs. Carbon has the least effective nuclear charge (Zeff) and so the lone pair on the CH3− ion has the highest energy, making it the least stable ion and so the strongest base. The Zeff increases as we move across the period until we get to fluorine which has the greatest Zeff and so its lone pairs have the lowest energy, making F− the least basic ion.

 

In order of decreasing basicity they are ranked LiCH3 > LiNH2 > LiOH > LiF. We are dealing with the ions F−, OH−, NH2− and CH3− and so the factor which influences their basicity is the stability of the ion compared to its conjugate acid.

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Filed Under: Chemistry
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2 5501
Q:

If Laxmi is taller than Ramya but shorter than Susmitha and Ramya is as tall as Hema but taller than Avanthi, then Hema is :

A) shorter than Ramya B) taller than Avanthi
C) taller than susmitha D) shorter than Laxmi
 
Answer & Explanation Answer: D) shorter than Laxmi

Explanation:

As given, we have:

Susmitha > Laxmi > Ramya; Ramya = Hema, Ramya > Avanthi

Thus the sequence of heights becomes:

Susmitha > Laxmi > Ramya = Hema > Avanthi

Clearly, Hema is shorter than Laxmi.

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Filed Under: Logical Sequence of Words
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14 5492
Q:

The compound interest on a certain sum for 2 years at 10% per annum is Rs. 1155. The simple interest on the same sum for double the time at half the rate percent per annum is ?

A) Rs. 1100 B) Rs. 5500
C) Rs. 1400 D) Rs. 4120
 
Answer & Explanation Answer: A) Rs. 1100

Explanation:

Let the sum be Rs.x. Then, 

 

 x1+101002-x=1155

 

x11102-1=1155

 

=> x =5500

 

sum = Rs. 5500.

 

So, S.I = Rs. 5500×5×4100 = 1100

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2 5488
Q:

Buses start from a bus terminal with a speed of 20 km/hr at intervals of 10 minutes. What is the speed of a man coming from the opposite direction towards the bus terminal if he meets the buses at intervals of 8 minutes?

A) 5 kmph B) 6 kmph
C) 7.5 kmph D) 8 kmph
 
Answer & Explanation Answer: A) 5 kmph

Explanation:

Let p be the speed of man in kmph

According to the given data in the question,

Distance travelled by bus in 10 min with 20 kmph == Distance travelled by man in 8 min with (20 + p) kmph in opposite direction

=> 20 x 10/60 = 8/60 (20 + p)

=> 200 = 160 + 8p

=> p = 40/8 = 5 kmph.

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11 5481
Q:

Area of a square and a rectangle are equal. If side of the square is 40 cm and length of the rectangle is 64 cm, what is the perimeter of the rectangle ?

A) 187 cm B) 178 cm
C) 149 cm D) 194 cm
 
Answer & Explanation Answer: B) 178 cm

Explanation:

Area of square = 40 x 40

= 1600 sq.cm

Given that the areas of Square and Rectangle are equal

=> Area of rectangle = 1600 Sq.cm

We know that, Area of rectangle = L x B

Given L = 64 cm

Breadth of rectangle = 1600/64 = 25 cm

Perimeter of the rectangle = 2(L + B) = 2(64+25) = 178 cm.

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32 5477
Q:

Two persons Shyam and Rahim can do a job in 32 days together. Rahim can do the same job in 48 days alone. They started working together and after working 8 days Rahim is replaced by a third person Ram whose efficiency is half that of Rahim. Find in how many days the remaining work will be completed by both Shyam and Ram together?

A) 16 days B) 72/5 days
C) 15 days D) 96/5 days
 
Answer & Explanation Answer: B) 72/5 days

Explanation:

Work done by Shyam and Rahim in 8 days = 8/32 = 1/4

Remaining work to be done by Shyam and Ram = 1 - 1/4 = 3/4

Given efficieny of Ram is half of Rahim i.e, as Rahim can do the work in 48 days, Ram can do the work in 24 days.

One day work of Ram and Shyam = (1/32 - 1/48) + 1/24 = 5/96

Hence, the total work can be done by Shyam and Ram together in 96/5 days.

 

Therefore, remaining work 3/4 can be done by them in 3/4 x 96/5 = 72/5 = 14.4 days.

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Filed Under: Time and Work
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