Showing 51–60 of 96 questions
Which statement about elastic collisions is correct?
A
Momentum is not conserved
B
Kinetic energy is conserved
C
Objects always stick together
D
Maximum energy is lost
Correct Answer:
B. Kinetic energy is conserved
Explanation:
In elastic collisions, both momentum and kinetic energy are conserved
What is the young's modulus of a material?
A
Stress/Strain
B
Strain/Stress
C
Force × Area
D
Force/Volume
Correct Answer:
A. Stress/Strain
Explanation:
Young's modulus Y = Stress/Strain = (F/A)/(ΔL/L), a measure of material stiffness
A convex lens of focal length 20 cm is used as a magnifying glass. If an object is placed 5 cm from the lens, what is the nature of the image?
A
Real, inverted, diminished
B
Virtual, erect, magnified
C
Real, erect, diminished
D
Virtual, inverted, magnified
Correct Answer:
B. Virtual, erect, magnified
Explanation:
When object is between lens and focus (u < f), a convex lens produces virtual, erect, magnified image
A car moving at 72 km/h applies brakes and comes to rest in 8 seconds. What is the deceleration?
A
2.5 m/s²
B
2.0 m/s²
C
1.5 m/s²
D
3.0 m/s²
Correct Answer:
A. 2.5 m/s²
Explanation:
First convert 72 km/h = 20 m/s. Using v = u + at: 0 = 20 + a(8), so a = -20/8 = -2.5 m/s². Magnitude of deceleration is 2.5 m/s².
Which of the following elements has an electronic configuration of 2, 8, 7?
A
Chlorine
B
Bromine
C
Fluorine
D
Iodine
Correct Answer:
A. Chlorine
Explanation:
Chlorine (Cl) has atomic number 17, with electronic configuration 2, 8, 7 (K-shell: 2, L-shell: 8, M-shell: 7).
The refractive index of a medium is 1.5. What is the speed of light in that medium? (c = 3 × 10⁸ m/s)
A
1.5 × 10⁸ m/s
B
2 × 10⁸ m/s
C
2.5 × 10⁸ m/s
D
3 × 10⁸ m/s
Correct Answer:
B. 2 × 10⁸ m/s
Explanation:
Refractive index n = c/v. Therefore, v = c/n = (3 × 10⁸)/1.5 = 2 × 10⁸ m/s.
A spring with spring constant k = 100 N/m is compressed by 0.2 m. What is the elastic potential energy stored?
Explanation:
Elastic potential energy U = ½kx². U = ½ × 100 × (0.2)² = 50 × 0.04 = 2 J.
Which hormone is responsible for regulating blood glucose levels?
A
Adrenaline
B
Insulin
C
Thyroxine
D
Cortisol
Correct Answer:
B. Insulin
Explanation:
Insulin, produced by the pancreas, lowers blood glucose by facilitating glucose uptake into cells. Glucagon raises blood glucose levels.
A 5 kg object is lifted vertically at constant velocity. What is the work done by gravity? (Height = 10 m, g = 10 m/s²)
A
-500 J
B
500 J
C
0 J
D
100 J
Correct Answer:
A. -500 J
Explanation:
Work by gravity W = -mgh (negative because displacement is opposite to force direction). W = -5 × 10 × 10 = -500 J.
What is the equivalent resistance when three resistors of 6Ω, 3Ω, and 2Ω are connected in parallel?
Explanation:
For parallel connection: 1/R = 1/6 + 1/3 + 1/2 = 1/6 + 2/6 + 3/6 = 6/6 = 1. Therefore R = 1Ω.
