What is the atomic mass unit (amu) equivalent to in kg?
A
1.66 × 10⁻²⁷ kg
B
1.66 × 10⁻²⁴ kg
C
1.66 × 10⁻³⁰ kg
D
1.66 × 10⁻³³ kg
Correct Answer:
A. 1.66 × 10⁻²⁷ kg
Explanation:
1 amu = 1.66054 × 10⁻²⁷ kg. This is used to express atomic and molecular masses.
Which law states that the force of attraction between two masses is directly proportional to the product of their masses and inversely proportional to the square of the distance between them?
A
Newton's First Law
B
Newton's Second Law
C
Newton's Law of Gravitation
D
Kepler's First Law
Correct Answer:
C. Newton's Law of Gravitation
Explanation:
Newton's Law of Universal Gravitation states F = G(m₁m₂)/r². This is the fundamental law describing gravitational attraction between masses.
Which of the following is NOT a vector quantity?
A
Displacement
B
Temperature
C
Velocity
D
Acceleration
Correct Answer:
B. Temperature
Explanation:
Temperature is a scalar quantity as it has only magnitude. Displacement, velocity, and acceleration are vector quantities as they have both magnitude and direction.
Which of the following has the lowest refractive index?
A
Water
B
Glass
C
Air
D
Diamond
Explanation:
Air has a refractive index of approximately 1, which is the lowest among common materials
What is the angle of incidence when light ray falls on a plane mirror and the angle of reflection is 35°?
Explanation:
According to law of reflection, angle of incidence equals angle of reflection
Which phenomenon explains the formation of a rainbow?
A
Refraction and dispersion
B
Reflection only
C
Diffraction only
D
Interference only
Correct Answer:
A. Refraction and dispersion
Explanation:
Rainbows form due to refraction of sunlight entering water droplets and dispersion of different wavelengths
What is the SI unit of pressure?
A
Bar
B
Pascal
C
Atm
D
Torr
Correct Answer:
B. Pascal
Explanation:
Pascal (Pa) is the SI unit of pressure, equal to 1 N/m²
A car moving at 20 m/s suddenly applies brakes with deceleration of 5 m/s². How far does it travel before stopping?
A
20 m
B
40 m
C
60 m
D
80 m
Explanation:
Using v² = u² + 2as, where v = 0, u = 20 m/s, a = -5 m/s². We get s = 400/10 = 40 m
Which of the following is NOT a SI base unit?
A
Ampere
B
Kelvin
C
Newton
D
Mole
Correct Answer:
C. Newton
Explanation:
Newton is a derived unit (kg⋅m⋅s⁻²). Ampere, Kelvin, and Mole are SI base units
A body is thrown vertically upward with a velocity of 40 m/s. What is the maximum height reached? (Take g = 10 m/s²)
A
80 m
B
40 m
C
160 m
D
120 m
Explanation:
Using v² = u² - 2gh, where final velocity v = 0, u = 40 m/s, g = 10 m/s². We get h = 1600/20 = 80 m
