A steel wire has length 6 m, cross-sectional area 3 mm² and Young's modulus 2 × 10¹¹ N m⁻². A 4 kg block is attached to its free end on a planet where g is one-fourth of Earth's value. Take gₑ = 10 m s⁻². The elongation is:
Options

Question

A steel wire has length 6 m, cross-sectional area 3 mm² and Young's modulus 2 × 10¹¹ N m⁻². A 4 kg block is attached to its free end on a planet where g is one-fourth of Earth's value. Take gₑ = 10 m s⁻². The elongation is:

Options

G1 Physics · Accepted Answer

On the planet: g = 10/4 = 2.5 m s⁻² F = mg = 4 × 2.5 = 10 N Young's modulus: Y = FL/(AΔL) Thus: ΔL = FL/(AY) = (10 × 6)/[(3 × 10⁻⁶)(2 × 10¹¹)] = 10⁻⁴ m = 0.1 mm Hence option C.