Answer:
the height of the porch is H=1.91 m
Step-by-step explanation:
neglecting friction and assuming that the porch is horizontal, then the horizontal speed is v₀= 4 m/s and it does not change , thus he hits the base at
t= L/v₀ , L= horizontal distance
then for vertical motion , since the vertical velocity vy is 0 , the initial height is H ( the height of the porche) and the final height hf is 0 , we have
hf = H + vy*t - 1/2*g*t²
0 = H + 0 -1/2*g*t²
H = 1/2*g*t² = 1/2*g*(L/v₀)²
replacing values with g= gravity = 9.8 m/s²
H = 1/2*g*(L/v₀)² = 1/2*9.8 m/s² *( 2.5 m/ 4 m/s)² = 1.91 m
therefore the height of the porch is H=1.91 m
