Question

Difficulty: HardSimple Harmonic Motion

A body of mass 0.50 kg0.50\text{ kg} connected to a light helical spring of force constant 32 N/m32\text{ N/m} executes simple harmonic motion on a smooth horizontal surface. If the total mechanical energy of the oscillating system is 0.16 J0.16\text{ J}, what is the maximum speed of the body in m/s\text{m/s}?

Answer: 0.8 m/s

Answer

The maximum speed of the body is 0.8 m/s0.8\text{ m/s}.
The total mechanical energy in simple harmonic motion is equal to the maximum kinetic energy at the equilibrium position: E=12mvmax2E = \frac{1}{2} m v_{\text{max}}^2. Substituting E=0.16 JE = 0.16\text{ J} and m=0.50 kgm = 0.50\text{ kg} yields 0.16=0.25vmax20.16 = 0.25 v_{\text{max}}^2, so vmax2=0.64v_{\text{max}}^2 = 0.64 and vmax=0.8 m/sv_{\text{max}} = 0.8\text{ m/s}.

Step-by-Step Solution

1
Relate total energy to maximum kinetic energy
E=12mvmax2E = \frac{1}{2} m v_{\text{max}}^2
At the equilibrium position, potential energy is zero and total mechanical energy is entirely kinetic.
2
Substitute given values into the equation
0.16=12(0.50)vmax20.16 = \frac{1}{2} (0.50) v_{\text{max}}^2
Mass m=0.50 kgm = 0.50\text{ kg} and total energy E=0.16 JE = 0.16\text{ J} are provided.
3
Solve for the maximum speed
vmax=2×0.160.50=0.64=0.8 m/sv_{\text{max}} = \sqrt{\frac{2 \times 0.16}{0.50}} = \sqrt{0.64} = 0.8\text{ m/s}
Solving for vmaxv_{\text{max}} gives 0.8 m/s0.8\text{ m/s}.

Key Concept

Conservation of Energy in Simple Harmonic Motion
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