A rock (m=2kg) is shot up vertically at the same time that a ball (m=0.5kg) is projected horizontally. If both start from the same height then

Explanation

The correct answer is that the ball will reach the ground first. When the rock is shot upwards, it experiences a delay in reaching the ground due to its initial upward motion which counteracts gravity for a time. The ball, on the other hand, is projected horizontally and is immediately influenced by gravity, making it fall directly downwards. Therefore, the ball reaches the ground before the rock. Option A is incorrect because both objects do not fall simultaneously due to different initial motions. Option B is incorrect because the rock takes longer to return to the initial height before falling. Option D is incorrect as their different trajectories prevent them from colliding.