Past exam of the physics 1 paper of the University of Oxford / 2017 / 7 / i / Solution

With no drag force, the horizontal velocity graph is a horizontal line at $v_0\cos \theta$. The vertical velocity graph is a straight line with initial value $v_0\sin \theta$ and gradient $-g$:For an upward launch, it crosses zero at the highest point, $t=v_0\sin \theta /g$. The ground-to-ground flight ends at $t=2v_0\sin \theta /g$, where $v_y=-v_0\sin \theta$. The left panel below shows these components; any continuation after ground contact is only the formal free-flight model.