Answer:
after sliding halfway down the plane ( at 0.1275 m from the bottom) the potencial gravitational energy is 2.5 J
Explanation:
the gravitational potential energy with respect to the bottom is
E = m * g * h
h = E/ (m*g)
replacing values
h= 5 J / (0.5 kg * 9.8 m/s²) = 0.255 m
also
h = d * sin Ф , where d= inclined plane distance , Ф = angle with respect to the horizontal plane
for halfway down the plane d2 =d/2 ,
since h2=d2* sin Ф = (d/2) * sin Ф = (d* sin Ф)/2 = h/2
h2=h/2 = 0.255 m/2 = 0.1275 m
thus
E2 = m*g*h2= (m*g*h)/2 = E/2 = 5 J /2 = 2.5 J
the potential energy E2 is 2.5 J