If a ball is thrown vertically upwards with speed u, the

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If a ball is thrown vertically upwards with speed u, the distance covered during the last t seconds of its ascent is

1. (u + gt) t
2. ut
3. 1/2 gt²
4. ut - 1/2 gt²

Correct Option: C

Let body takes T sec to reach maximum height.
Then v = u – gT
v = 0, at highest point. T = u/g …(1)
Velocity attained by body in (T – t) sec v = u – g (T – t)

= u – gT + gt = u – g	u	+ gt
	g

or v = gt …(2)

∴ Distance travelled in last t sec of its ascent

s = (gt)t -	1	gt² =	1	gt²
	2		2