MCQ help Watch
Which of the following gives the acceleration of the ball at various stages in its motion? Take vertically upwards as positive. Neglect air resistance.
A. rising -g , at maximum height 0, falling +g
B. rising -g , at maximum height -g, falling -g
C. rising g, at maximum height g, falling g
D. rising g, at maximum height 0 , falling -g
The answer was given B. Why??
Imagine a velocity-time graph, the graph will slope downwards until from when the ball is released until it hits his hand again, thus a negative acceleration.
The ball is always accelerating downwards, because its under gravity.
Up is defined as positive in the question so the acceleration must always be negative.
What a c rap question.
When it moves upward, the velocity decrease to zero which then means deceleration thus -9.81..
When it falls down, itll be negative since th question said take vertically upwards as positive(even when the velocity increase) *if u understand my explaination