Pre-ecat 2019 (Group: F.Sc Pre Engineering)

Two forces of magnitudes 12 N and 13 N act on a body. Which one of the following is not possible resultant of these two vectors?

• 1 N

• 20 N

• 25 N

• 31 N

The period of oscillation of a simple pendulum is given by  whereas L is about 100 cm and is known to have 1 mm accuracy. This period is about 2 s. The time for 100 oscillations is measured by a stop watch of least count 0.1 s. The percentage error in 'g' is: 

• 0.1%

• 1%

• 0.2%

• 0.8%

A 50 grams bullet is moving with velocity 10 meter per second strikes a block of mass 950 grams at rest and gets embedded in it. The loss in Kinetic energy will be:

• 100%

• 95% 

• 5% 

• 50% 

Two cars, initially next to each other and at rest, accelerate in the same straight line at different uniform rates. After 3 seconds , they are x meters. If they continue to accelerate , at same rate how far apart will they be 6 seconds after they started?

• Y=24 x

• Y=x

•  y=4 x

• Y=12 x

A mixture of two gas at constant temperature contains the molecules of two kinds. The first kind of mass m₁ and root mean square speed c₁ and the second molecule of mass m₂ and rms speed c₂. The ratio of  is:

• M₁/m₂

• M₂/m₁

For the velocity-time graph, as shown in the figure below, the total distance covered by a body in all seven seconds will be:

• 20 meters

• 60 meters

• 40 meters

• 80 meters

A shell is fired at angle of  45 degrees above the ground with the initial velocity of 100 meter per second . It will hit the ground, assuming g=10 meter per square second, after about;

• 7 seconds

• 10 seconds

• 14 seconds

• 20 seconds

The v-t graph of a moving object is given in figure. The maximum acceleration is

• 1 meter per square second

• 2 meter per square second

• 3 meter per square second

• 6 meter per square second

A boy is standing near a building. Eventually, a bomb is blasted at the distant place from the observer. Why does the boy feel tremor before it hears the sound of blast? 

• Speed of waves are faster in air than that of the speed in the ground

• Elastic modulus of solid is much greater than that of the elastic modulus of gas

• Speed of sound in the solid is  much lesser than that of the speed in the air

• Both A & B

Three particles A,B and C are thrown from the top of a tower with the same speed. A is thrown up, B is thrown down and C is thrown horizontally. They hit the ground with speeds V_A, V_B, and V_C respectively;

• V_A=V_B=V_C

• V_A=V_B>V_C

• V_B>V_C>V_A

• V_A>V_B=V_C

A weight lifter lifts 300 kilograms from the ground to height of 2 meters in 3 seconds. The average power generated by him is:

• 5880 watts 

• 4410 watts

• 2205 watts

• 1960 watts

Two satellites of masses m₁ and m₂ (m₁ > m₂) are revolving around the earth in circular orbits of radii r₁ and r₂ (r₁ > r₂) respectively. Which of the following statements is true regarding their speeds v₁ and  v₂  ?

• V₁=v₂

• V₁ > v₂

• V₁ < v₂

• V₁/r₁ = v₂/r₂

If the critical angle for the total internal reflection from a medium to vacuum is 30°. The velocity of light in the medium is:

• 3 × 10⁸ m/s

• 1.5 × 10⁸ m/s

• 6 × 10⁸ m/s

•  × 10⁸ m/s

In the following fig. is shown the flow of liquid through a horizontal pipe. Three tubes A, B and C are connected to the pipe. The radii of the tubes A, B and C at the junction are respectively 2 cm 1 cm and 2 cm, it can be said that the

• Height of the liquid in the tube A is maximum

• Height of the liquid in the tubes A and B is the same

• Height of the liquid in all the three tubes is the same

• Height of the liquid in the tubes A and C is the same

The maximum percentage efficiency of engine operating between 227°C and 7 °C? 

• 56%

• 40%

• 44%

• 50%

The displacement of a particle executing Simple Harmonic motion is half of its magnitude. The fraction of its Kinetic energy will be:

• 2/3

• 1/3

• 3/4

• 1/2

A motor cycle running at 130 km/hr sounds a siren of 2 kHz frequency while chasing a car running at 150 km/h. The apparent frequency of the siren heard by the car driver will be:

• Less than 2 kHz

• Equal to 2 kHz

• Greater than 2 kHz

• The siren will not heard by the car driver

If 15/16 of the the radioactive element decays in 8 minutes the half life of the radioactive element is:

• 8 min

• 4 min

• 2 min

• 12 min

A thermistor with positive temperature is used to measure the temperature in an oven. When the temperature of the oven increases, the value of resistance of thermistor:

• Decreases

• Incresaes

• Remains unchanged

• None of the above

The relationship between X and Y in the following diagram

• Y=X

• Y'= X

• Y=X'

• Both B & C

The current in a resistor is 8.0 mA. How many number of electrons flows through the resistor in 0.020 seconds?

• 1  electrons

• 1 electrons

• 1

• 1

You have 15 capacitors available with you, each of 15 nF. You need a capacitance of around 150 nF in a circuit. You can achieve this value by connecting:

• 10 capacitors in series

• 10 capacitors in parallel

• 12 capacitors in series

• 8 capacitors in parallel

Three similar light bulbs are connected to a constant DC supply as shown in the diagram. Each bulb operates at normal brightness and an ammeter of a negligible resistance registers a steady current. One more similar bulb is connected in parallel to the three bulbs. What happens to the ammeter reading and the brightness of the four bulbs?

• Ammeter reading increases and brightness also increases

• Ammeter reading increases and brightness remains unchanged

• Ammeter reading remains unchanged; bulb brightness remains unchanged

• Ammeter reading decreases and brightness remains unchanged

Semi-conductor behaves as _________ at 0 K

• Insulators

• Superconductors

• Pure conductors

• None of these

When light falls on the metal surface, the maximum kinetic energy of the emitted photo-electrons depends upon:

• The time for which light falls on the metal

• Frequency of incident light

• Intensity of incident light

• Velocity of the incident light

A wire loop is placed in between the poles of magnet as shown in the figure below: If the wire loop is rotated in the clockwise direction around the axis. Which of the following statement regarding the instantaneous current in PQ segment is correct?

• The direction of the current will be from P to Q

• The direction of the current will be from Q to P

• There is no current

• The direction of the current in PQ segment will depend upon the the resistance of the load

Coherent monochromatic light illuminates two narrow parallel slits and interference pattern which results is observed on a screen some distance beyond the slits. Which of the following modification will increase the separation between the dark lines of the interference pattern?

• Using the monochromatic light of higher frequency

• Using the monochromatic light of higher wavelength

• Decreasing the distance between screen and slits

• Increasing the distance between slits

Two blocks of iron are heated to 200 °C and 400 °C respectively. Compared to 200 °C , the 400 °C block will emit the radiation of;

• Same wavelength

• Larger wavelength

• Smaller wavelength

• Lower frequency

A person standing on a weighing scale in a lift going upwards with constant velocity. If the weight of the person under the normal circumstances is W. The weight shown by the weighing scale in the lift will be?

• Less than W

• Greater than W

• Equal to W

• May be less than or greater than W depending upon the speed of the lift

Mathematics: (Question 31 to 60)  'A'  can do a piece of work in 16 days while 'B' can do it in 12 days, with the help of 'C' they can finish it in 6 days. In how many days can C alone do the work?

• 48 days

• 10 days

• 20 days

• 30 days

The sum of the ages of a son and a father is 64. After 4 years, the age of father will be three times that of his son's age. The age of the father is:

• 46 years

• 44 years

• 50 years

• 45 years

Two vectors are perpendicular to each other. The positive value of "a" will be:

• 4

• 3

• 9

• 13

Two vectors are parallel to each other then the value of  will be;

• 0

• 2

• -2

• 4

Additive inverse of the complex number, is;

Polar form of is;

• All of these

Two lines, 

• L and M are parallel to each other

• L and M are perpendicular to each other

• Both L and M are perpendicular and parallel to each other

• Neither L and M are perpendicular nor parallel to each other

The function for has point of maximum at,

• (1,5)

• (5,1)

• (3,4)

• (2,2)

The general solution of is;

If the line joining is parallel to the line joining , then value of 'k' is :

• 2/23

• 23/2

• 11

• -11

The angle C of the triangle ABC, in which is;

If 

• 45° or 315°

• 60° or 300°

• 30° or 330°

• None of these

If the term independent of 'x' in the expression  is 45/4 then;

• K=1/2

• |k|=1/2

• K=-1/2

• |k|=2

If then;

Ifthen a+b is

• 3

• -2

• 1

• -1

There are 15 boys and 10 girls in a class. If three are selected at random. What is probability that 1 girl and  2 boys are selected:

The inequality , which satisfies the intervals:

Area enclosed by the curve and the x-axis from is same as:

• All of these

• 21

• -21

• -7

• 7