I am not able to understand acceleration sums please help experts

Dear Student

These questions are to be done using equations of motion with constant acceleration:
1-$$\begin{gathered} 2- \\ v=u+at \\ v=5+0.5*40=25 m/s is final speed \\ 3- \\ v=u+at \\ v=0+5*10=50 m/s is final velocity \\ 4- \\ v=u+at \\ a=\frac{v-u}{t}=\frac{50-0}{25}=2 m/s^2 \\ 5- \\ a) v^2=u^2+2gh=0^2+2*10*20=400 \\ v with which it hit ground=20 m/s \\ b)v=u+at \\ t=\frac{v-u}{a}=\frac{20-0}{10}=2 s \\ Regards \end{gathered}$$