Archimedes' principle is used in MCQ with Answer and Explanation

Explanation:
Doppler effect: observed frequency higher when approaching, lower when receding. Applications: radar speed guns, astronomical redshift/blueshift, echocardiography. Echo is reflection. Resonance is vibration matching. Diffraction is bending.

Explanation:
Angular momentum (L = mvr) has dimensions [ML²T⁻¹]. Planck's constant (h = E/ν) also has dimensions [ML²T⁻¹]. They share the same dimensional formula. Force is [MLT⁻²], Power is [ML²T⁻³], Momentum is [MLT⁻¹], and Strain is a dimensionless quantity [M⁰L⁰T⁰]. This is a frequent exam question.

Explanation:
Average speed = total distance / total time = d / ( (d/2)/v1 + (d/2)/v2 ) = 2v1v2/(v1+v2).