If you are already familiar with basics of circular motion, skip straight to the question. The theoretical background brought below contains clues for the answer.
In physics, circular motion is a movement of an object along the circumference of a circle or rotation along a circular path. Examples of circular motion include: an artificial satellite orbiting the Earth at constant height, a stone which is tied to a rope and is being swung in circles, a car turning through a curve in a race track, an electron moving perpendicular to a uniform magnetic field and many more.
Since the object's velocity vector is constantly changing direction, the moving object is undergoing acceleration by a centripetal force in the direction of the center of rotation. Without this acceleration, the object would move in a straight line, according to Newton's laws of motion. If we take, for example, a marble rotating inside a cone, the forces acting on the marble are shown below:
N- the normal force- is applied by the surface perpendicularly. The horizontal component of the Normal force is the centripetal force, which keeps the marble rotating around the glass circumference.
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The dual-lingual movies are explaining the material well and coherent.
The qustion itself requires understanding of the phenomenon of the normal force
and the need of upward force vector to make the ball climb up.
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