Question

A ball is dropped from a platform 19.6 m high. Its position function is:

• A. \(x=-4.9t^2+19.6\;(0\le t\le1)\)
• B. \(x=-4.9t^2+19.6\;(0\le t\le2)\)
• C. \(x=-9.8t^2+19.6\;(0\le t\le2)\)
• D. x=-4.9t²-19.6(0≤ t\le2)

Hint:

For a dropped body, initial velocity is zero.

Answer 1

The Correct Option is B

Step 1: Equation of motion: x=ut-(1)/(2)gt²+h
Step 2: Here u=0, g=9.8, h=19.6 x=19.6-4.9t²
Step 3: Time to reach ground: 19.6=4.9t²⟹ t=2