The mirror used as rear-view mirror in vehicles is
A. Plane mirror
B. Parabolic mirror
C. Convex mirror
D. Concave mirror
Answer: Option C
Solution (By JKSSB Mock Tests)
Convex mirror gives wider field of view, always forms virtual, erect, diminished image. Allows driver to see larger area. Concave can magnify but field narrow. Plane gives normal view but limited field.
Explanation:
In SHM, a = -ω²x, acceleration ∝ -displacement. Minus sign indicates direction towards mean position (restoring). Characteristic of SHM. Pendulum and spring-mass system exhibit SHM for small displacements.
Explanation:
Escape velocity v_e = √(2GM/R), where M is planet mass, R its radius. Thus v_e depends on both M and R. It is independent of the escaping body's mass (as gravitational and inertial mass cancel). Memory tip: 'v_e ∝ √(M/R); larger M or smaller R ⇒ higher escape velocity'. This gravitation formula application is frequently tested in competitive exams. Always recall that escape velocity is a property of the planet, not the projectile. This problem assesses understanding of gravitational potential energy concepts.
Explanation:
The Doppler Effect is the apparent change in the frequency (and thus pitch) of a wave due to the relative motion between the source and the observer. As the ambulance approaches, sound waves get compressed, increasing the perceived frequency (higher pitch). As it moves away, waves stretch, lowering the frequency.
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