A rock is thrown upwards at 5 m/s from the top of a building 80 m high. When will it hit the ground (to the nearest tenth of a second)?
A) 4.6 s
B) 4.1 s
C) 3.6 s
D) 3.1 s
E) 5.1 s

Question

Quizplus · Accepted Answer

The time it takes for the rock to hit the ground can be calculated using the kinematic equation: $ h = v_i t + \frac{1}{2} g t^2 $, where $ h $ is the height (80 m), $ v_i $ is the initial velocity (5 m/s), and $ g $ is the acceleration due to gravity (approximately 9.8 m/s²). Solving this quadratic equation gives the time as approximately 4.6 seconds.

A Rock Is Thrown Upwards at 5 M/s from the Top