A ball is thrown upwards and it returns to the ground describing a parabolic path. Which of the following rema

Question

A ball is thrown upwards and it returns to the ground describing a parabolic path. Which of the following remains constant?

Accepted Answer

1.  **Force Analysis:** In projectile motion (neglecting air resistance), the only force acting on the body is the force of gravity, which acts vertically downwards. There is no force acting in the horizontal direction .
2.  **Acceleration:** Since force is zero in the horizontal direction, the horizontal acceleration ($a_x$) is zero. In the vertical direction, the acceleration is constant ($a_y = -g$) .
3.  **Velocity Components:** 
    *   Since $a_x = 0$, the **horizontal component of velocity** ($v_x$) remains constant throughout the motion.
    *   Since $a_y 
eq 0$, the vertical component of velocity ($v_y$) changes continuously.
4.  **Speed and Kinetic Energy:** The speed ($v = \sqrt{v_x^2 + v_y^2}$) and kinetic energy ($K = \frac{1}{2}mv^2$) depend on $v_y$, so they change during the flight (decreasing during ascent and increasing during descent).

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