A child with mass of 25 kg gets into a toy car with mass of 80 kg on a playground, causing it to sink on its springs (with effective spring constant 791 N/m). An adult walks by and gives the top of the car a shove, causing it to undergo oscillations with amplitude 31 cm in the vertical direction. Assuming the oscillations are simple harmonic, what is the frequency of the oscillations?

The frequency of the oscillation is 0.9Hz

Explanation:

This problem bothers on simple harmonic motion of a spring

Given data

Mass of the child m= 25kg

Spring constant k=791 N/m

Amplitude a= 31cm

But the period of the motion as a result of the adults sholve is expressed as

T=2π√m/k

T=2*3.142√25/791

T=6.284√0.031

T=6.284*0.176

T=1.11 sec

But frequency F=1/T

F=1/1.11

F=0.9Hz

a and b sometimes have a positive value

real, smaller and upside-down.   so the answer should be b.