The following plots show variation of velocity (v) with time (t), of a ball thrown vertically upward, and falling back. Which of the following plots is/are correct? [figure]
- B only
- A and E only
- C only
- D only
Answer
(3) C only
Solution
Take upward as positive: v = u - gt ⇒ v–t graph is a straight line of constant slope -g.
v starts positive, decreases to zero at the highest point and then becomes negative (ball falling down).
∴ Only plot C, a straight line of negative slope crossing the t-axis, is correct.
Answer: (3)