Answer:
![a = 0.53 m/s^2](https://img.qammunity.org/2020/formulas/physics/college/6mribym197gxm9syww5h56brjjuhiu0sov.png)
Step-by-step explanation:
initially the merry go round is at rest
after 6.73 s the merry go round will accelerates to 20 rpm
so final angular speed is given as
![\omega = 2\pi f](https://img.qammunity.org/2020/formulas/physics/middle-school/pwzsovla2h22uvtixjbu2t72piygxnka5a.png)
![\omega = 2\pi ( (20)/(60))](https://img.qammunity.org/2020/formulas/physics/college/h1bxt6fes91vjyxxn6afxuk7zskyq3jevr.png)
![\omega = 2.10 rad/s](https://img.qammunity.org/2020/formulas/physics/college/d4jeh4rgt0lk78hwv3531c70iqpp62opjp.png)
so final tangential speed is given as
![v = r\omega](https://img.qammunity.org/2020/formulas/physics/middle-school/tl9o4le1v0uy88jtrc4kzjo6ebrd9feuft.png)
![v = 1.71 (2.10) = 3.58 m/s](https://img.qammunity.org/2020/formulas/physics/college/i8rlidkpj0ktn6omdjcy21ephnqlvzg35h.png)
now average acceleration of the girl is given as
![a = (v_f - v_i)/(\Delta t)](https://img.qammunity.org/2020/formulas/physics/high-school/6vsyyxqnrw20l2yy1zpgt3u5lz4xow27v0.png)
![a = (3.58 - 0)/(6.73)](https://img.qammunity.org/2020/formulas/physics/college/i8zuhyaworrxwqoq76x8sgve2ohvty1kyz.png)
![a = 0.53 m/s^2](https://img.qammunity.org/2020/formulas/physics/college/6mribym197gxm9syww5h56brjjuhiu0sov.png)