An automobile can be considered to be mounted on four identical springs as far as vertical oscillations are concerned. The springs of a certain car are adjusted so that the oscillations have a frequency of 4 Hz.
(a) What is the spring constant of each spring if the mass of the car is 1450 kg and the weight is evenly distributed over the springs?
[[[[ i figured this out.. and the answer is: 2.28e5 N/m ]]]]
(b) What will be the vibration frequency if five passengers, averaging 77.0 kg each, ride in the car with an even distribution of mass? ___ Hz
.. im not sure what im doing wrong here..
sqrt((2.28e5)/(1450+5(77))) = 11.14 rads/s
11.14 / 2pi = 1.75 Hz
.. should i be adding the weight of the passengers including the weight of the car on the springs? .. i feel like im soo close to the answer, but i cant grasp what's wrong. please help!
sqrt (k/m) = w
k= w^2 * m= (16*4*PI^2)*1450
k of each spring is k/4=16PI^2*1450= 2.29E5 N/m
Now change the mass
w= sqrt k/m= sqrt (2.29E5*4/1835)=41.35
f= w/2PI=6.58 hz
check that.
6 answers