Question

a projectile is launched from the ground at an angle of 30 degrees. at what point in its trajectory does this projectile have the least speed a. just after it was launched b. at the highest point in its flight c. just before it hits the ground d. halfway between the ground and its highest point e. the speed is always constant

Explanation:

The initial velocity of a projectile has both horizontal and vertical components. The horizontal component of velocity ($v_x$) remains constant throughout the motion as there is no acceleration in the horizontal - direction (assuming no air - resistance). The vertical component of velocity ($v_y$) changes due to the acceleration of gravity. At the highest point of the projectile's trajectory, the vertical component of velocity is zero. The speed of the projectile is given by $v = \sqrt{v_x^{2}+v_y^{2}}$. Since $v_x$ is constant and $v_y = 0$ at the highest point, the speed $v$ is minimum at the highest point of the flight.

Answer:

B. At the highest point in its flight