Physics Test

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Physics Test - 4

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Question 1
4 / -1

An AND gate has four inputs A, B, C, D. The input that produces an output 1 is

A
0000

B
1000

C
0001

D
1111

Solution

An AND gate always produces an output 1, only when all the inputs are 1.
Question 2
4 / -1

Forces of magnitudes 3 and 2 units acting in the direction respectively act on a particle which is displaced from the points (1,-1,-1) to (3,3,1) . The work done by the forces is equal to

A
80√2 units

B
40√2 units

C

D
8√2 units

Solution
Question 3
4 / -1

The net work done by a net force acting on an object is equal to the change in the kinetic energy of the object. It is known as:

A
Work-Force theorem

B
Work-Kinetic energy theorem

C
Potential energy theorem

D
Force-Kinetic energy theorem

Solution

The Work-Kinetic energy theorem states that the net work done by a net force acting on an object is equal to the change in the kinetic energy of the object.

Kinetic energy is the energy possessed by an object due to its motion or movement. In simple words, it is the energy of motion, observable as the movement of an object, particle, or set of particles.
Question 4
4 / -1

For a transistor, the current amplification factor is 0.8. If the transistor is in common emitter configuration and the base current changes by 6 mA, the change in the collector current is

A
6 mA

B
4.8 mA

C
24 mA

D
8 mA

Solution
Question 5
4 / -1

A boatman can row with a speed of 10 kmh^–1. If a river of width 2 km flows at 5 kmh^–1, then what is the direction in which the boatman should row to reach a point on the other bank directly opposite to the point from where he started?

A
Along the flow

B
60° in NW

C
90° to the direction of flow

D
120° to the direction of flow

Solution
Question 6
4 / -1

A rod, 1 m long, made of a material of thermal conductivity 420 W/m/K has one of its ends in melting ice and the other end in boiling water. If its cross-sectional area is 10 cm², then the amount of ice that melts in 1 minute is

A
0.125 g

B
75 g

C
7.5 g

D
450 g

Solution

हम पाते हैं
Question 7
4 / -1

The condition for a uniform spherical mass 'm' of radius 'r', to be a black hole is ______________.

[G = gravitational constant and g = acceleration due to gravity]

A

B

C

D

Solution

Is the necessary condition for a spherical mass m of radius r to be a black hole.
Question 8
4 / -1

In the following question, a statement of Assertion is given, followed by a corresponding statement of Reason. Mark the correct answer as:

(a) If both Assertion and Reason are true and the Reason is the correct explanation of the Assertion.

(b) If both Assertion and Reason are true, but the Reason is not the correct explanation of the Assertion.

(c) If Assertion is true, but Reason is false.

(d) If both Assertion and Reason are false.

Assertion: The earth is slowing down and as a result the moon is coming nearer to it.

Reason: The angular momentum of the earth-moon system is not conserved.

A
(a)

B
(b)

C
(c)

D
(d)

Solution

Planetary motions can exist only if they obey the law of conservation of angular momentum. If this law is violated, then no gravitational law will be able to explain the behaviour of the planets and the satellites.
Question 9
4 / -1

A body moving along the circular path of radius `R` describes an angle of 60o at the center of the circle, while moving from A to B. The displacement of the body is

A
R/2

B
R

C
√3R

D
√2R

Solution
Question 10
4 / -1

Three rods made of the same material and having the same cross-section have been joined as shown in the figure below. Each rod is of the same length. The left and right ends are kept at 0^oC and 90^oC, respectively. The temperature of the junction of the three rods will be

A
45^oC

B
60^oC

C
30^oC

D
20^oC

Solution

Let A and l be the area of cross-section and the length of each rod. If k is the coefficient of thermal conductivity and f∘C the temperature of the junction O, then the rates at which heat energy enters O from rods A and B are

In the steady state, rate at which heat energy enters O= rate at which heat energy leaves O, i.e.