Hello!
The answer are:
For the first exercise:
a).
![004(m)/(s^(2) )](https://img.qammunity.org/2020/formulas/physics/middle-school/af081dmxyxzaeingg2n62lg7yeazcbu68a.png)
For the second exercise:
b).
![.0056(m)/(s^(2) )](https://img.qammunity.org/2020/formulas/physics/middle-school/fvkpwe3g1wjszrvw0ojj6bpvissog07mla.png)
Why?
For boths question we will use the following formula:
![Vf=Vi+a*t\\a=(Vf-Vi)/(t)](https://img.qammunity.org/2020/formulas/physics/middle-school/zv0pin7aeg2iwlzrxvab5gkyvm4els0itl.png)
First, let's convert mph to mps:
For the first exercise:
![(60mile)/(h)*(1h)/(60min)*(1min)/(60seconds)=(60m)/(3600s)=(0.0166m)/(s)](https://img.qammunity.org/2020/formulas/physics/middle-school/hvpzk3obqpchp9fcextfmltm4y9q8qi49u.png)
So,
![60mph=0.0166mps](https://img.qammunity.org/2020/formulas/physics/middle-school/wyw0m3gkbni1f2wo76i0e3dk43d3sw887c.png)
For the second exercise:
![(100mile)/(h)*(1h)/(60min)*(1min)/(60seconds)=(100m)/(3600s)=(0.0277m)/(s)](https://img.qammunity.org/2020/formulas/physics/middle-school/mg5b1nasqzbg6sg8r42074k4xpbxzdezwt.png)
So,
![100mph=0.0277mps](https://img.qammunity.org/2020/formulas/physics/middle-school/ijop38v5lhhcp8nonebqco0uxk5javjyw4.png)
So, for the first exercise:
![0.0166=0+a*4\\a=(0.0166-0)/(4)=0.004(m)/(s^(2) )](https://img.qammunity.org/2020/formulas/physics/middle-school/7srvnbvf85t156thywgcvngi5mf66zr0s0.png)
Then, for the second exercise:
![0.0277=0+a*5\\a=(0.0277-0)/(5)=0.0056(m)/(s^(2) )](https://img.qammunity.org/2020/formulas/physics/middle-school/tdzjsxjphlt7mjsabalcuwhb73xkb72m11.png)
Have a nice day!