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
1
What primary physical factor enables an aircraft to execute aerobatic maneuvers, such as a vertical loop?
Answer:
Gravity
The provided answer attributes the maneuver to gravity. While aerobatics rely on thrust-to-weight ratios and aerodynamic lift, the question frames gravity as the enabling factor. In a vertical loop, the aircraft must overcome gravity to maintain its path. Note: There is an EXPLANATION_CONFLICT as standard physics usually attributes the circular path to centripetal force, while gravity acts as a resistive force during the climb phase of the loop.
2
If an object completes two full revolutions along a circular path of radius R, what is the ratio of its total displacement to the total distance covered?
Answer:
0
Displacement is defined as the straight-line distance between the initial and final positions. Since the object completes two full revolutions, it returns to its starting point, making the total displacement zero. Consequently, the ratio of displacement to the distance covered (which is 4πR) is zero.
3
What is the physical purpose of banking railway tracks on curved sections?
Answer:
Necessary centripetal force may be obtained from the horizontal component of the weight of the train
When a train travels along a curve, it requires a centripetal force to maintain its circular path. By banking the tracks (tilting the outer rail higher than the inner rail), the normal force exerted by the track on the train provides a horizontal component that acts as the necessary centripetal force, reducing reliance on friction.
4
A body starts from rest and slides down a smooth plane inclined at an angle θ with the horizontal. What is the time taken to reach the bottom if the vertical height is h?
Answer:
$$\frac{1}{{\sin \theta }}\sqrt {\frac{{2h}}{g}} $$
The acceleration down the plane is a = g sin θ. The length of the incline is l = h / sin θ. Using s = 1/2 at^2, we get l = 1/2 (g sin θ) t^2. Substituting l, we find t^2 = 2h / (g sin^2 θ), so t = (1/sin θ) * sqrt(2h/g).
5
From which cardinal direction does the measurement of azimuth typically originate?
Answer:
North
In navigation and astronomy, an azimuth is an angular measurement in a spherical coordinate system. By standard convention, the azimuth angle is measured clockwise from the true North point on the horizon to the vertical circle passing through the object.
6
When a bottle containing liquid and air bubbles is swung rapidly in a vertical circle, where do the bubbles tend to accumulate?
Answer:
Near the neck
When the bottle is swung, the liquid, being denser than the air bubbles, experiences a greater centrifugal force directed outward toward the bottom of the bottle. Consequently, the denser liquid is pushed to the outer edge, displacing the lighter air bubbles toward the center of rotation, which is the neck of the bottle.
7
What is the approximate maximum flight speed of a falcon?
Answer:
200 kmh-1
The peregrine falcon is known for its high-speed hunting dive, known as a stoop. During this maneuver, it can reach speeds exceeding 200 km/h, making it one of the fastest animals in the world. This speed is a standard reference in biological kinematics.
8
What is the primary purpose of banking a road?
Answer:
skidding of vehicle
Banking a road involves tilting the surface at a curve to provide a component of the normal force that acts toward the center of the turn. This centripetal force helps the vehicle maintain its path without relying solely on friction, thereby preventing the vehicle from skidding outward.
9
If an object completes exactly two revolutions along 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 exactly to its initial position, resulting in a net displacement of zero. The distance traveled is the circumference multiplied by the number of revolutions (4πR). The ratio of displacement (0) to distance (4πR) is therefore 0 divided by 4πR, which equals zero.
10
A cyclist travels along a semicircular track with a radius of 420 meters, completing the journey in 3 minutes. Calculate the magnitude of the average velocity.
Answer:
4.67 ms−1
Average velocity is defined as displacement divided by time. For a semicircular path, the displacement is the diameter (2r = 840 m). The time is 3 minutes, which equals 180 seconds. Thus, velocity = 840 / 180 = 4.666... ms⁻¹, which rounds to 4.67 ms⁻¹.