Question

9(d)(i) Define bulk modulus. (ii) A vertical wire is suspended from a support with a mass of 2.5g attached to the free end to stretch the wire. If the load on the wire extends it by 2 cm, determine the energy gained by the wire. [g = 10 ms⁻²]

Accepted Answer

(i) Bulk modulus is the ratio of the very small increase in pressure applied to a material to the resulting relative decrease in its volume: k = −ΔP/(ΔV/V) (Pa), where ΔP is the change in pressure, ΔV is the change in volume, and V is the original volume. The negative sign shows that an increase in pressure leads to a decrease in volume.
(ii) F = mg = 2.5×10⁻³×10 = 0.025 N; e = 0.02 m. Energy gained, W = ½Fe = ½×0.025×0.02 = 2.5×10⁻⁴ J.

WAEC Physics 2025 Theory — Question 15

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