Answer:
Part a)
![A = 1.78 m](https://img.qammunity.org/2020/formulas/physics/high-school/ojrvahzx5vwdxqiz3zdqnfui5n2f9ndpj3.png)
Part b)
![f = 2 rev/s](https://img.qammunity.org/2020/formulas/physics/high-school/8lv24esrdfkzodgnc57t12vsbs3igj7sa3.png)
Step-by-step explanation:
Part A)
As we know that time period of the motion is given as
![T = 2.68 s](https://img.qammunity.org/2020/formulas/physics/high-school/3jd4z8wsecnjlr9zqjbduanc675zfftsgo.png)
so we have
![\omega = (2\pi)/(T)](https://img.qammunity.org/2020/formulas/physics/middle-school/cxl2h8f7s9zvqaly4lhdcx78m1u1mdzcug.png)
![\omega = (2\pi)/(2.68)](https://img.qammunity.org/2020/formulas/physics/high-school/6un5eg9xgypigkqga5hb4hfknzqonrskwo.png)
![\omega = 2.34 rad/s](https://img.qammunity.org/2020/formulas/physics/high-school/p93a1qrspttgeqy4npkxrt64tw0hu7qbny.png)
now at the point of maximum amplitude the force equation when Normal force is about to zero is given as
![mg = m\omega^2 A](https://img.qammunity.org/2020/formulas/physics/high-school/texf2hd1hraq6k59iq217hobncpf0qhn4a.png)
so we have
![A = (g)/(\omega^2)](https://img.qammunity.org/2020/formulas/physics/high-school/2j3tviylx8pfzpct6bhk2k3ggk2bn3srll.png)
![A = (9.81)/(2.34^2)](https://img.qammunity.org/2020/formulas/physics/high-school/yg2iqmfdb4e04ax67ug1xomeexr0jpo9c4.png)
![A = 1.78 m](https://img.qammunity.org/2020/formulas/physics/high-school/ojrvahzx5vwdxqiz3zdqnfui5n2f9ndpj3.png)
Part b)
Now if the amplitude of the SHM is 6.23 cm
and now at this amplitude if object will lose the contact then in that case again we have
![mg = m\omega^2 A](https://img.qammunity.org/2020/formulas/physics/high-school/texf2hd1hraq6k59iq217hobncpf0qhn4a.png)
![g = \omega^2 (0.0623)](https://img.qammunity.org/2020/formulas/physics/high-school/fhsfrlz4qcj8c242foi04tzau7oqqkmidp.png)
![\omega = 12.5 rad/s](https://img.qammunity.org/2020/formulas/physics/high-school/f4ecp8m0og8we8ku5km5yxw30w7smeanz9.png)
so now we have
![2\pi f = 12.5](https://img.qammunity.org/2020/formulas/physics/high-school/ur79xkma5f89tenyacpvgwyllccqc1hx2y.png)
![f = 2 rev/s](https://img.qammunity.org/2020/formulas/physics/high-school/8lv24esrdfkzodgnc57t12vsbs3igj7sa3.png)