Attempt each question, then reveal the answer to mark yourself.
Question 1 — Units
The SI unit of force is the
A. Joule
B. Newton
C. Watt
D. Pascal
Answer: B. Force is measured in newtons (N). The joule measures energy/work, the watt measures power, and the pascal measures pressure.
Question 2 — Speed vs Velocity
Which of the following is a vector quantity?
A. Speed
B. Distance
C. Mass
D. Velocity
Answer: D. Velocity has both magnitude and direction, so it is a vector. Speed, distance and mass are scalars.
Question 3 — Acceleration
A body accelerates uniformly from rest to 30 m/s in 6 s. Its acceleration is
A. 5 m/s²
B. 0.2 m/s²
C. 36 m/s²
D. 180 m/s²
Answer: A. a = (v − u)/t = (30 − 0)/6 = 5 m/s².
Question 4 — Newton’s Second Law
A net force of 12 N acts on a mass of 3 kg. The acceleration produced is
A. 36 m/s²
B. 9 m/s²
C. 4 m/s²
D. 0.25 m/s²
Answer: C. a = F/m = 12/3 = 4 m/s².
Question 5 — Ohm’s Law
A potential difference of 6 V is applied across a resistor carrying 2 A. The resistance is
A. 12 Ω
B. 0.33 Ω
C. 3 Ω
D. 8 Ω
Answer: C. R = V/I = 6/2 = 3 Ω.
Question 6 — Theory
State Newton’s three laws of motion.
Answer:
1. A body remains at rest or in uniform motion in a straight line unless acted upon by an external force. 2. The rate of change of momentum is proportional to the applied force and occurs in the direction of the force (F = ma). 3. For every action there is an equal and opposite reaction.
Question 7 — Theory
A mass of 4 kg falls from a height of 20 m. Taking g = 10 m/s², calculate its potential energy before falling.
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