When a ball is thrown up vertically from a height and the falls to the ground, the various kinematic graphs below shows the same motion of the ball. Fixing up as positive, if the ball is going up, it’s displacement and velocity will be in the positive region. When it falls, the direction is opposite, hence it’s in the negative portion. Recall that the gradient of a velocity-time graph represents the acceleration. Using this concept, it will be easier to understand that the acceleration is a negative constant acceleration, thus – 10 ms-2. (acceleration is 10 ms-2 downwards towards earth)

Using the formula n = 1/sin c, the higher the n , the smaller the c . With smaller c , total internal reflection can occur over a wider range of angle of incidences . i.e. the optical fibre can bend more and total internal reflection can still occur.

There are two main types of balancing toys. Type 01: CG below the pivot point Type 02: CG above the pivot

This video goes through the basic concepts that is required for moment questions. Go through the whole video to have know the different types of questions.