Physics MCQs
Topic Notes: Physics
MCQs and preparation resources for competitive exams, covering important concepts, past papers, and detailed explanations.
Plato
- Biography: Ancient Greek philosopher (427–347 BCE), student of Socrates and teacher of Aristotle, founder of the Academy in Athens.
- Important Ideas:
- Theory of Forms
- Philosopher-King
- Ideal State
11
An object completes two full revolutions around a circular path of radius R. What is the ratio of its total displacement to the total distance traveled?
Answer:
0
Displacement is defined as the change in position from the starting point to the ending point. Since the object completes two full revolutions, it returns to its initial position, making the net displacement zero. The total distance traveled is 4πR (two circumferences). The ratio of displacement (0) to distance (4πR) is therefore 0. This illustrates the fundamental difference between vector displacement and scalar distance.
12
What condition regarding speed must be met for water to remain inside a pail swung in a vertical circle at the top of the loop?
Answer:
Above a certain minimum value irrespective of amount of water in the pail
To keep water in the pail at the top of a vertical loop, the centripetal acceleration must be at least equal to the acceleration due to gravity. This requires a minimum critical velocity, v = sqrt(gr). Since the mass of the water cancels out in the force equation (mg = mv^2/r), the required speed is independent of the mass or amount of water in the pail.
13
What is the physical reason a cyclist leans inward when navigating a turn?
Answer:
Necessary centripetal force may be available from the horizontal component of the normal reaction due to the track to maintain the curved motion.
When a cyclist leans, the normal force from the ground is no longer purely vertical. The horizontal component of this normal force provides the necessary centripetal force to keep the cyclist moving in a circular path. This allows the cyclist to turn without relying solely on friction, which might be insufficient on slippery surfaces.
14
What is the correct expression for the angle of inclination a cyclist must maintain to prevent skidding during a turn?
Answer:
-1
The physics of a cyclist turning involves balancing centripetal force with gravity. The angle of inclination θ is determined by the relationship tan(θ) = v² / (rg). The provided answer key suggests 'B' (-1), which is mathematically inconsistent with the standard physical derivation of the banking angle for a cyclist.