Raindrops fall to the ground with a uniform, constant velocity. This constant velocity is achieved when the gravitational pull is perfectly balanced by: MCQ with Answer and Explanation
Raindrops fall to the ground with a uniform, constant velocity. This constant velocity is achieved when the gravitational pull is perfectly balanced by:
A. Buoyant force alone
B. Viscous drag force alone
C. Surface tension of the drop
D. The sum of viscous drag force and buoyant force
Answer: Option D
Solution (By JKSSB Mock Tests)
As a raindrop falls, it accelerates due to gravity. The upward viscous drag force of the air increases with the drop's velocity (Stokes' Law). Eventually, the downward weight of the drop is exactly balanced by the upward buoyant force of the air plus the upward viscous drag force. The net force becomes zero, and it falls with a constant 'terminal velocity'.
Explanation:
Nuclear fusion: e.g., hydrogen isotopes deuterium and tritium fuse to helium, releasing energy. Powers Sun and stars. Requires high temperature (thermonuclear). Fusion reactor under development.
Explanation:
SONAR (Sound Navigation and Ranging) uses ultrasonic waves (frequency > 20 kHz) because they have high directionality, short wavelength for better resolution, and minimal absorption in water. Radio waves attenuate rapidly in water; infrasonic waves have long wavelengths unsuitable for detection; light doesn't propagate far in water. Memory tip: 'Ultra = beyond human hearing; used in SONAR/ultrasound imaging'. This application question tests knowledge of wave frequency ranges and their practical uses, common in competitive exams linking physics to technology. Always recall frequency thresholds: infrasonic 20kHz.
No comments yet. Be the first to start the discussion!