You thoughtfully set a 1 kg box on top of a loaf of bread and the loaf compresses by 15 cm. Thinking of the bread as a spring, its spring constant is
A) 1 N/m
B) 0.653 N/m
C) 65.3 N/m
D) 0.015 N/m

Question

Quizplus · Accepted Answer

The spring constant $k$ can be found using Hooke's Law, $F = kx$, where $F$ is the force applied and $x$ is the displacement (compression in this case). The force applied by the 1 kg box is due to gravity, $F = mg$, where $m = 1 \, \text{kg}$ and $g \approx 9.8 \, \text{m/s}^2$, so $F = 9.8 \, \text{N}$. The displacement $x = 15 \, \text{cm} = 0.15 \, \text{m}$. Substituting these values into Hooke's Law gives $k = \frac{F}{x} = \frac{9.8}{0.15} \approx 65.3 \, \text{N/m}$.

You Thoughtfully Set a 1 Kg Box on Top of a Loaf