Jiayang's answer to Vivian Yang's Secondary 3 E Maths question.
thank you! Just an additional clarification qn. For the ball qn, is it that magnitude of acceleration is always constant, but while the ball is heading upwards acceleration is negative, but when it's heading downwards, acceleration is positive?
No. Acceleration is a vector. If we define from the very beginning downwards as negative then it'll be negative.