Question

Difficulty: MediumSimple Harmonic Motion

A body of mass 0.40 kg0.40\text{ kg} is attached to a light helical spring and set into simple harmonic motion. If the system oscillates with a period of 0.40π s0.40\pi\text{ s}, what is the force constant of the spring in N/m\text{N/m}?

Answer: 10 N/m

Answer

The force constant of the spring is 10 N/m10\text{ N/m}.
The period of a mass-spring system undergoing simple harmonic motion is given by T=2πmkT = 2\pi \sqrt{\frac{m}{k}}. Substituting m=0.40 kgm = 0.40\text{ kg} and T=0.40π sT = 0.40\pi\text{ s} yields 0.40π=2π0.40k0.40\pi = 2\pi \sqrt{\frac{0.40}{k}}. Dividing both sides by 2π2\pi gives 0.20=0.40k0.20 = \sqrt{\frac{0.40}{k}}. Squaring both sides yields 0.04=0.40k0.04 = \frac{0.40}{k}, which gives k=10 N/mk = 10\text{ N/m}.

Step-by-Step Solution

1
Identify the period relationship for a spring-mass SHM system
T=2πmkT = 2\pi \sqrt{\frac{m}{k}}
This formula relates the period of oscillation TT to the mass mm and spring constant kk.
2
Substitute the given mass and period into the equation
0.40π=2π0.40k0.40\pi = 2\pi \sqrt{\frac{0.40}{k}}
Given that m=0.40 kgm = 0.40\text{ kg} and T=0.40π sT = 0.40\pi\text{ s}.
3
Simplify the equation by isolating the square root term
0.40k=0.20\sqrt{\frac{0.40}{k}} = 0.20
Dividing both sides of the equation by 2π2\pi isolates the radical.
4
Square both sides and solve for the spring constant kk
k=10 N/mk = 10\text{ N/m}
Squaring yields 0.04=0.40k0.04 = \frac{0.40}{k}, which rearranges to k=0.400.04=10 N/mk = \frac{0.40}{0.04} = 10\text{ N/m}.

Key Concept

Period of oscillation of a mass-spring system in Simple Harmonic Motion
Estimated Time:1m 30s
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