Question

A child stands on the edge of the cliff $10 m$ above the ground and throws a stone horizontally with an initial speed of $5 \,ms ^{-1}$ Neglecting the air resistance, the speed with which the stone hits the ground will be ______$ms ^{-1}$ (given, $g=10 \,ms ^{-2}$ )

• A. 15
• B. 20
• C. 30
• D. 25

Answer 1

Answer: (A)

15

Answer 2

The correct answer is (A) : 15

$v_y=\sqrt{2gh}=\sqrt{200}$
$v_{net}=\sqrt{25+200}=\sqrt{225}$
= 15 m/s