Q. A damped harmonic oscillator has a mass of 2 kg and a damping coefficient of 0.5 kg/s. What is the damping ratio if the spring constant is 8 N/m?
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Solution
Damping ratio (ζ) = c / (2√(mk)) = 0.5 / (2√(2*8)) = 0.5 / (2√16) = 0.5 / 8 = 0.0625.
Correct Answer: B — 0.5
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Q. A damped oscillator has a time constant of 3 seconds. What is the amplitude after 6 seconds if the initial amplitude is 10 m?
A.
2.5 m
B.
5 m
C.
7.5 m
D.
10 m
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Solution
Amplitude after time t = A0 * e^(-t/τ) = 10 * e^(-6/3) = 10 * e^(-2) ≈ 2.5 m.
Correct Answer: A — 2.5 m
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Q. A damped oscillator has a time constant of 3 seconds. What is the damping coefficient if the mass is 1 kg and the spring constant is 4 N/m?
A.
1.5 kg/s
B.
2 kg/s
C.
3 kg/s
D.
4 kg/s
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Solution
Time constant (τ) = m/c, thus c = m/τ = 1/3 = 0.333 kg/s. Using c = 2ζ√(mk), we find ζ = 0.5.
Correct Answer: B — 2 kg/s
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Q. A data set has values: 10, 12, 14, 16. What is the variance? (2021)
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Solution
Mean = (10 + 12 + 14 + 16) / 4 = 13. Variance = [(10-13)² + (12-13)² + (14-13)² + (16-13)²] / 4 = 2.5.
Correct Answer: B — 4
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Q. A diamond has a refractive index of 2.42. What is the critical angle for total internal reflection at the diamond-air interface?
A.
24.4°
B.
41.1°
C.
23.6°
D.
17.5°
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Solution
Critical angle θc = sin^(-1)(1/n) = sin^(-1)(1/2.42) ≈ 24.4°.
Correct Answer: A — 24.4°
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Q. A die is rolled. What is the probability of getting a number greater than 4?
A.
1/6
B.
1/3
C.
1/2
D.
1/4
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Solution
Numbers greater than 4 are 5 and 6. Probability = 2/6 = 1/3.
Correct Answer: B — 1/3
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Q. A die is rolled. What is the probability of getting an even number given that the number rolled is greater than 2?
A.
1/2
B.
1/3
C.
2/3
D.
1/4
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Solution
The possible outcomes greater than 2 are {3, 4, 5, 6}. The even numbers among these are {4, 6}. Thus, the probability is 2/4 = 1/2.
Correct Answer: C — 2/3
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Q. A die is rolled. What is the probability of getting an even number?
A.
1/2
B.
1/3
C.
1/6
D.
2/3
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Solution
Even numbers on a die: 2, 4, 6. Probability = 3/6 = 1/2.
Correct Answer: A — 1/2
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Q. A die is rolled. What is the probability of rolling an even number given that the number rolled is greater than 2?
A.
1/2
B.
1/3
C.
1/4
D.
2/3
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Solution
The possible outcomes greater than 2 are {3, 4, 5, 6}. The even numbers among these are {4, 6}. Thus, the probability is 2/3.
Correct Answer: D — 2/3
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Q. A die is rolled. What is the probability of rolling an even number?
A.
1/2
B.
1/3
C.
1/6
D.
2/3
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Solution
The even numbers on a die are 2, 4, and 6, which gives us 3 favorable outcomes. The total outcomes are 6. Therefore, the probability is 3/6 = 1/2.
Correct Answer: A — 1/2
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Q. A diet consists of 60% carbohydrates, 25% proteins, and 15% fats. If a person consumes 2000 calories, how many calories come from proteins? (2000)
A.
300 calories
B.
400 calories
C.
500 calories
D.
600 calories
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Solution
25% of 2000 calories = 0.25 * 2000 = 500 calories.
Correct Answer: B — 400 calories
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Q. A dipole consists of two charges +q and -q separated by a distance d. What is the dipole moment?
A.
qd
B.
q/d
C.
q^2d
D.
q/d^2
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Solution
The dipole moment p = q * d.
Correct Answer: A — qd
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Q. A dipole consists of two charges +q and -q separated by a distance d. What is the expression for the dipole moment?
A.
qd
B.
q/d
C.
q^2d
D.
q/d^2
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Solution
The dipole moment p is defined as p = q * d.
Correct Answer: A — qd
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Q. A dipole consists of two equal and opposite charges separated by a distance 'd'. What is the dipole moment? (2023)
A.
qd
B.
q/d
C.
q^2d
D.
qd^2
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Solution
The dipole moment (p) is defined as p = qd, where q is the charge and d is the separation distance.
Correct Answer: A — qd
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Q. A dipole consists of two equal and opposite charges separated by a distance of 0.1m. What is the dipole moment if each charge is 1μC?
A.
1 × 10^-7 C m
B.
1 × 10^-6 C m
C.
1 × 10^-5 C m
D.
1 × 10^-4 C m
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Solution
Dipole moment p = q * d = (1 × 10^-6 C) * (0.1 m) = 1 × 10^-7 C m.
Correct Answer: B — 1 × 10^-6 C m
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Q. A dipole consists of two equal and opposite charges separated by a distance. What happens to the dipole moment if the distance is doubled?
A.
It doubles
B.
It halves
C.
It remains the same
D.
It quadruples
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Solution
Dipole moment p = q * d, if d is doubled, p also doubles.
Correct Answer: A — It doubles
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Q. A dipole is placed in a uniform electric field. What is the torque experienced by the dipole? (2023)
A.
pE
B.
pE sin(θ)
C.
pE cos(θ)
D.
Zero
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Solution
The torque (τ) experienced by a dipole in a uniform electric field is given by τ = pE sin(θ), where p is the dipole moment and θ is the angle between p and E.
Correct Answer: B — pE sin(θ)
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Q. A dipole moment is defined as the product of charge and the distance between the charges. What is the dipole moment of a dipole consisting of charges +2μC and -2μC separated by 0.1m?
A.
4 × 10^-7 C m
B.
2 × 10^-7 C m
C.
2 × 10^-6 C m
D.
4 × 10^-6 C m
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Solution
Dipole moment p = q * d = (2 × 10^-6 C) * (0.1 m) = 2 × 10^-7 C m.
Correct Answer: A — 4 × 10^-7 C m
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Q. A dipole moment p is placed in a uniform electric field E. What is the torque experienced by the dipole?
A.
pE
B.
pE sin θ
C.
pE cos θ
D.
0
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Solution
Torque τ = p × E = pE sin θ, where θ is the angle between p and E.
Correct Answer: B — pE sin θ
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Q. A disc of mass M and radius R is rotating about its axis with an angular velocity ω. What is the angular momentum of the disc?
A.
(1/2)MR^2ω
B.
MR^2ω
C.
MRω
D.
(1/4)MR^2ω
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Solution
Angular momentum L = Iω, where I = (1/2)MR^2 for a disc.
Correct Answer: A — (1/2)MR^2ω
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Q. A disc of radius R and mass M is rotating about its axis with an angular velocity ω. What is the kinetic energy of the disc?
A.
(1/2)Iω^2
B.
(1/2)Mω^2
C.
Iω
D.
Mω^2
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Solution
Kinetic energy K = (1/2)Iω^2, where I = (1/2)MR^2 for a disc.
Correct Answer: A — (1/2)Iω^2
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Q. A disc of radius R and mass M is rotating about its axis with an angular velocity ω. What is its kinetic energy?
A.
(1/2)Iω^2
B.
(1/2)Mω^2
C.
(1/2)M(R^2)ω^2
D.
(1/2)(MR^2)ω^2
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Solution
The moment of inertia I of a disc about its axis is (1/2)MR^2. Therefore, the kinetic energy K.E. = (1/2)Iω^2 = (1/2)(1/2)MR^2ω^2 = (1/4)MR^2ω^2.
Correct Answer: D — (1/2)(MR^2)ω^2
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Q. A disc of radius R and mass M is rotating about its axis with an angular velocity ω. What is its angular momentum? (2020)
A.
Iω
B.
MωR²
C.
0.5MR²ω
D.
MR²ω
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Solution
The moment of inertia I of a disc about its axis is (1/2)MR². Therefore, angular momentum L = Iω = (1/2)MR²ω.
Correct Answer: A — Iω
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Q. A disc of radius R and mass M is rotating about its axis with an angular velocity ω. What is the moment of inertia of the disc? (2020)
A.
(1/2)MR²
B.
(1/3)MR²
C.
MR²
D.
(1/4)MR²
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Solution
The moment of inertia of a solid disc about its central axis is given by I = (1/2)MR².
Correct Answer: A — (1/2)MR²
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Q. A disc of radius R and mass M is rotating about its axis with an angular velocity ω. What is its rotational kinetic energy? (2020)
A.
(1/2)Iω²
B.
(1/2)Mω²
C.
Iω
D.
Mω²
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Solution
Rotational kinetic energy K.E. = (1/2)Iω². For a disc, I = (1/2)MR², thus K.E. = (1/4)MR²ω².
Correct Answer: A — (1/2)Iω²
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Q. A disc rolls without slipping on a horizontal surface. If its radius is R and it rolls with a linear speed v, what is its angular speed?
A.
v/R
B.
2v/R
C.
v/2R
D.
v^2/R
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Solution
The relationship between linear speed and angular speed for rolling without slipping is ω = v/R.
Correct Answer: A — v/R
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Q. A discount of 15% is given on a product that costs $120. What is the final price after the discount?
A.
$102
B.
$108
C.
$110
D.
$100
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Solution
Discount = 15% of $120 = $120 * 0.15 = $18. Final Price = $120 - $18 = $102.
Correct Answer: B — $108
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Q. A discount of 15% on a marked price results in a selling price of $255. What was the marked price?
A.
$300
B.
$280
C.
$270
D.
$250
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Solution
Let the marked price be x. After a 15% discount, the selling price is 0.85x. Setting this equal to $255 gives 0.85x = $255, so x = $255 / 0.85 = $300.
Correct Answer: A — $300
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Q. A discount of 25% on a product results in a selling price of $150. What was the original price? (2023)
A.
$175
B.
$200
C.
$225
D.
$250
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Solution
Let the original price be x. Then, Selling Price = x - (25% of x) = 150 => 0.75x = 150 => x = 200.
Correct Answer: B — $200
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Q. A disk and a ring of the same mass and radius are released from rest at the same height. Which one reaches the ground first?
A.
Disk
B.
Ring
C.
Both reach at the same time
D.
Depends on the surface
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Solution
The disk has a lower moment of inertia compared to the ring, thus it reaches the ground first.
Correct Answer: A — Disk
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