Question Detail
Question
A stone of mass 20 kg is thrown vertically upward to attain a maximum height of 20 m. Calculate the initial speed with which the stone was thrown.
Correct Answer
Option B is the correct answer.
Detailed Explanation
Using the kinematic equation v² = u² - 2gh, where v=0 at the top, h=20 m, g=10 m/s². So 0 = u² - 21020 => u² = 400 => u = 20 m/s.
Hint
At maximum height, the final velocity is zero. Use v² = u² - 2gh.