chapters of Halliday’s Principles of Physics, Extended, International Adaptation,
12th Edition. Each question is followed by a detailed rationale explaining the
underlying concepts. You can use these questions to review and test your
understanding of mechanics, thermodynamics, waves, electromagnetism,
modern physics, and more.
Question 1 – Measurement and Units
Question: Which of the following is the SI unit for force?
a) Joule
b) Newton
c) Pascal
d) Watt
Answer: b) Newton
Rationale:
Force is defined as mass times acceleration. The SI unit for mass is the kilogram and for acceleration is
meters per second squared; their product gives the newton. This unit is named after Sir Isaac Newton,
reflecting his contribution to classical mechanics.
Question 2 – Vectors and Components
Question: A particle moves with a velocity of 10 m/s at an angle of 30° above the horizontal. What is the
horizontal component of the velocity?
a) 5 m/s
b) 8.66 m/s
c) 10 m/s
d) 15 m/s
Answer: b) 8.66 m/s
Rationale:
The horizontal component vxv_xvx is found using the cosine of the angle:
vx=vcosθ=10cos(30°)≈10×0.866=8.66 m/s.v_x = v \cos\theta = 10 \cos(30°) \approx 10 \times 0.866
= 8.66 \text{ m/s}.vx=vcosθ=10cos(30°)≈10×0.866=8.66 m/s.
Understanding vector components is crucial in analyzing two-dimensional motion.
Question 3 – Newton’s Laws of Motion
, Question: An object of mass 5 kg is accelerated at 4 m/s². According to Newton’s second law, what is
the net force acting on the object?
a) 9 N
b) 20 N
c) 5 N
d) 10 N
Answer: b) 20 N
Rationale:
Newton’s second law states F=maF = maF=ma. Here, m=5 kgm = 5 \text{ kg}m=5 kg and a=4 m/s2a = 4
\text{ m/s}^2a=4 m/s2, so F=5×4=20 NF = 5 \times 4 = 20 \text{ N}F=5×4=20 N. This fundamental law
links force, mass, and acceleration.
Question 4 – Work and Energy
Question: A force of 50 N is applied to push a box along a horizontal surface for a distance of 3 m. How
much work is done by the force?
a) 150 J
b) 53 J
c) 50 J
d) 100 J
Answer: a) 150 J
Rationale:
Work is defined as the product of the force component in the direction of displacement and the
distance:
W=F×d=50 N×3 m=150 J.W = F \times d = 50 \text{ N} \times 3 \text{ m} = 150 \text{
J}.W=F×d=50 N×3 m=150 J.
This question reinforces the concept that work is a scalar quantity measured in joules.
Question 5 – Momentum and Collisions
Question: Two objects, A (mass = 2 kg, velocity = 3 m/s) and B (mass = 4 kg, velocity = -2 m/s), collide.
What is the total momentum before the collision?
a) 2 kg·m/s
b) 0 kg·m/s
c) 4 kg·m/s
d) -2 kg·m/s
Answer: a) 2 kg·m/s
Rationale:
Momentum is given by p=mvp = mvp=mv. Calculate momentum for each: