The wavelength of a wave is the distance between two consecutive MCQ with Answer and Explanation

Explanation:
For equal distances: average speed = total distance/total time = 2d/(d/v₁ + d/v₂) = 2v₁v₂/(v₁+v₂). This is harmonic mean, not arithmetic. Memory tip: Equal distances ⇒ harmonic mean of speeds; equal times ⇒ arithmetic mean. Frequently tested kinematics concept distinguishing average speed calculation methods.

Explanation:
R_t = R₀(1+α t). 6 = 4(1+0.004 t) => 1.5 = 1+0.004t => 0.5=0.004t => t=125°C.

Explanation:
g' = g (R/(R+h))² = g (1/2)² = g/4. Weight = 100/4 = 25 N.