Question

A missile was thrown from the top of the Himalayas to Kanyakumari. In absence of air resistance, this motion can be best categorized as

• A. One dimensional motion
• B. Two dimensional motion
• C. Three dimensional motion
• D. None of these

Answer 1

The correct option is B

Two dimensional motion

Lets assume that we are standing on a perfectly horizontal plane on the top of the mountain and we launch our missile at ${45}^{\circ }$ to the horizontal. You can imagine that to be a motion in 1D the missile should always keep going in the same path, always making an angle of ${45}^{\circ }$. Basically the path has to be a straight line. But clearly you know that is not what happens in reality, as there is a force that pulls everything down; yeah right, gravity. So, every moment the ball will be dragged down and its velocity's vertical component will keep on reducing until it hits the surface. This proves that the motion is not 1D . The ball while going south towards Kanyakumari moves up and then down due to gravity so it is 2D motion. Basically there is an initial velocity in one direction and acceleration in other, such a kind of motion will always be 2D.