Step 1: Use the formula for weight at depth.- Weight on surface: W = mg = 400N.- At depth d = R/2,
Step 2: Substitute the values.
W' = W(1 - dR)
W' = 400(1 - R/2R)
W' = 400(1 - 12)
W' = 400 $\cdot$ 12 = 200N
Final Answer: Weight at half the earth’s radius = 200N
Proton (P) and electron (e) will have same de-Broglie wavelength when the ratio of their momentum is (assume mp = 1849me):
Three infinitely long charge sheets are placed as shown in figure. The electric field at point P is


Gravitational force is a central force that depends only on the position of the test mass from the source mass and always acts along the line joining the centers of the two masses.
According to Newton’s law of gravitation, “Every particle in the universe attracts every other particle with a force whose magnitude is,
By combining equations (1) and (2) we get,
F ∝ M1M2/r2
F = G × [M1M2]/r2 . . . . (7)
Or, f(r) = GM1M2/r2 [f(r)is a variable, Non-contact, and conservative force]