Answer:
(a) vmax = 0.34m/s
(b) v = 0.13m/s
(c) v = 0.31m/s
(d) x = 0.039m
Explanation:
Given information about the spring-mass system:
m: mass of the object = 0.30kg
k: spring constant = 22.6 N/m
A: amplitude of the motion = 4.0cm = 0.04m
(a) The maximum speed of the object is given by the following formula:
(1)
w: angular frequency of the motion.
The angular frequency is calculated with the following relation:
(2)
You replace the expression (2) into the equation (1) and replace the values of the parameters:
![v_{max}=\sqrt{\frac{k}{m}}A=\sqrt{\frac{22.6N/m}{0.30kg}}(0.04m)=0.34\frac{m}{s}](https://tex.z-dn.net/?f=v_%7Bmax%7D%3D%5Csqrt%7B%5Cfrac%7Bk%7D%7Bm%7D%7DA%3D%5Csqrt%7B%5Cfrac%7B22.6N%2Fm%7D%7B0.30kg%7D%7D%280.04m%29%3D0.34%5Cfrac%7Bm%7D%7Bs%7D)
The maximum speed of the object is 0.34 m/s
(b) If the object is compressed 1.5cm the amplitude of its motion is A = 0.015m, and the maximum speed is:
![v_{max}=\sqrt{\frac{22.6N/m}{0.30kg}}(0.015m)=0.13\frac{m}{s}](https://tex.z-dn.net/?f=v_%7Bmax%7D%3D%5Csqrt%7B%5Cfrac%7B22.6N%2Fm%7D%7B0.30kg%7D%7D%280.015m%29%3D0.13%5Cfrac%7Bm%7D%7Bs%7D)
The speed is 0.13m/s
(c) To find the speed of the object when it passes the point x=1.5cm, you first take into account the equation of motion:
![x=Acos(\omega t)](https://tex.z-dn.net/?f=x%3DAcos%28%5Comega%20t%29)
You solve the previous equation for t:
![t=\frac{1}{\omega}cos^{-1}(\frac{x}{A})\\\\\omega=\sqrt{\frac{22.6N/m}{0.30kg}}=8.67\frac{rad}{s}\\\\t=\frac{1}{8.67}cos^{-1}(\frac{1.5cm}{4.0cm})=0.13s](https://tex.z-dn.net/?f=t%3D%5Cfrac%7B1%7D%7B%5Comega%7Dcos%5E%7B-1%7D%28%5Cfrac%7Bx%7D%7BA%7D%29%5C%5C%5C%5C%5Comega%3D%5Csqrt%7B%5Cfrac%7B22.6N%2Fm%7D%7B0.30kg%7D%7D%3D8.67%5Cfrac%7Brad%7D%7Bs%7D%5C%5C%5C%5Ct%3D%5Cfrac%7B1%7D%7B8.67%7Dcos%5E%7B-1%7D%28%5Cfrac%7B1.5cm%7D%7B4.0cm%7D%29%3D0.13s)
With this value of t, you can calculate the speed of the object with the following formula:
![v=\omega Asin(\omega t)\\\\v=(8.67rad/s)(0.04m)sin((8.67rad/s)(0.13s))=0.31\frac{m}{s}](https://tex.z-dn.net/?f=v%3D%5Comega%20Asin%28%5Comega%20t%29%5C%5C%5C%5Cv%3D%288.67rad%2Fs%29%280.04m%29sin%28%288.67rad%2Fs%29%280.13s%29%29%3D0.31%5Cfrac%7Bm%7D%7Bs%7D)
The speed of the object for x = 1.5cm is v = 0.31 m/s
(d) To calculate the values of x on which v is one-half the maximum speed, you first calculate the time t:
![\frac{v_{max}}{2}=\omega A sin(\omega t)\\\\t=\frac{1}{\omega}sin^{-1}(\frac{v_{max}}{2\omega A})\\\\t=\frac{1}{8.67rad/s}sin^{-1}(\frac{0.13m/s}{2(8.67rad/s)(0.04m)})=0.021s](https://tex.z-dn.net/?f=%5Cfrac%7Bv_%7Bmax%7D%7D%7B2%7D%3D%5Comega%20A%20sin%28%5Comega%20t%29%5C%5C%5C%5Ct%3D%5Cfrac%7B1%7D%7B%5Comega%7Dsin%5E%7B-1%7D%28%5Cfrac%7Bv_%7Bmax%7D%7D%7B2%5Comega%20A%7D%29%5C%5C%5C%5Ct%3D%5Cfrac%7B1%7D%7B8.67rad%2Fs%7Dsin%5E%7B-1%7D%28%5Cfrac%7B0.13m%2Fs%7D%7B2%288.67rad%2Fs%29%280.04m%29%7D%29%3D0.021s)
The position will be:
![x=Acos(\omega t)=0.04mcos((8.67rad/s)(0.021s))=0.039m](https://tex.z-dn.net/?f=x%3DAcos%28%5Comega%20t%29%3D0.04mcos%28%288.67rad%2Fs%29%280.021s%29%29%3D0.039m)
The position of the object on which its speed is one-half its maximum velocity is 0.039