Answer:
a) Her feet are in the air for 0.73+0.41 = 1.14 seconds
b) Her highest height above the board is 0.82 m
c) Her velocity when her feet hit the water is 7.16 m/s
Explanation:
t = Time taken
u = Initial velocity = 4 m/s
v = Final velocity
s = Displacement
a = Acceleration due to gravity = 9.81 m/s²
[tex]v=u+at\\\Rightarrow 0=4-9.81\times t\\\Rightarrow \frac{-4}{-9.81}=t\\\Rightarrow t=0.41\ s[/tex]
[tex]s=ut+\frac{1}{2}at^2\\\Rightarrow s=4\times 0.41+\frac{1}{2}\times -9.81\times 0.41^2\\\Rightarrow s=0.82\ m[/tex]
b) Her highest height above the board is 0.82 m
Total height she would fall is 0.82+1.8 = 2.62 m
[tex]s=ut+\frac{1}{2}at^2\\\Rightarrow 2.62=0t+\frac{1}{2}\times 9.81\times t^2\\\Rightarrow t=\sqrt{\frac{2.62\times 2}{9.81}}\\\Rightarrow t=0.73\ s[/tex]
a) Her feet are in the air for 0.73+0.41 = 1.14 seconds
[tex]v=u+at\\\Rightarrow v=0+9.81\times 0.73\\\Rightarrow v=7.16\ m/s[/tex]
c) Her velocity when her feet hit the water is 7.16 m/s
