Physics - W.E.P. Question with Solution | TestHub

During ascent, gravity acts downwards while vertical displacement is upwards, so work done by gravity is negative. Thus, A is correct. During descent, gravity acts downwards and vertical displacement is downwards, so work done by gravity is positive. Thus, B is correct. At the highest point, the vertical component of velocity is zero. The initial kinetic energy is $\frac{1}{2}m{v}_0^2$. The kinetic energy at the highest point is $\frac{1}{2}m(v_0\cos \alpha {)}^2$. The change in kinetic energy is $W_g=-mg{H}_{max}$. So, C is correct. The work-energy theorem states that the net work done by all forces on a particle equals the change in its kinetic energy. Thus, D is correct.