A retaining wall of height $H$ with smooth vertical backface supports a backfill inclined at an angle $\beta$ with the horizontal. The backfill consists of cohesionless soil having angle of internal friction $\phi .$ If the active lateral thrust acting on the wall is $P_{a},$ which one of the following statements is TRUE?
(A) $P_{a}$ acts at a height $H / 2$ from the base of the wall and at an angle $\beta$ with the horizontal
(B) $P_{a}$ acts at a height $H / 2$ from the base of the wall and at an angle $\phi$ with the horizontal
(C) $P_{a}$ acts at a height $H / 3$ from the base of the wall and at an angle $\beta$ with the horizontal
(D) $P_{a}$ acts at a height $H / 3$ from the base of the wall and at an angle $\phi$ with the horizontal
A retaining wall of height $H$ with smooth vertical backface supports a backfill inclined at an angle $\beta$ with the horizontal. The backfill consists of cohesionless soil having angle of internal friction $\phi .$ If the active lateral thrust acting on the wall is $P_{a},$ which one of the following statements is TRUE?
(A) $P_{a}$ acts at a height $H / 2$ from the base of the wall and at an angle $\beta$ with the horizontal
(B) $P_{a}$ acts at a height $H / 2$ from the base of the wall and at an angle $\phi$ with the horizontal
(C) $P_{a}$ acts at a height $H / 3$ from the base of the wall and at an angle $\beta$ with the horizontal
(D) $P_{a}$ acts at a height $H / 3$ from the base of the wall and at an angle $\phi$ with the horizontal
$P_{a}$ acts at a height $H / 3$ from the base of the wall and at an angle $\beta$ with the horizontal