The answer is 24.805 seconds. I accidently wrote the distance instead of time but deleted the comment. So if you don't count my answer, I understand. I did more work than I needed to.

g=-9.8 m/s (gravity)
s = 15 m/s (speed)

3000= -g/2(t^2) - s(t) = -4.9t^2 + 15 --> Solve for t and you get t=15(sqrt(134)/7))=24.805 seconds.

Answer for Day 15 Math Problem

25.53 seconds 🎯

Solution

The formula for the time it takes for a projectile to land on the ground from a platform higher than the ground is the following:

t = [v * sin(a) + sqrt((v * sin(a))² + 2 * g * h)] / g

where

v = initial velocity
a = angle from horizontal
g = acceleration due to gravity
h = elevated platform

Our original problem has the following information:

height = 3 kilometers = 3,000 meters
angle from horizontal = 30°
initial velocity = 15 meters per second = 15 m/s

Our equation now is the following:

v = [(15 m/s) * sin(30°) + sqrt((15 m/s * sin(30°))² + 2 * 9.81 m/s * 3000 m)] / 9.81 m/s

The equation without the units (though the units in the answer will be in seconds) to make it easier to put into a calculator:

v = [15 * sin(30°) + sqrt((15 * sin(30°))² + 2 * 9.81 * 3000)] / 9.81

The answer is v = 25.53073137 seconds.

Winner: none 🤯

Since there is no winner for today, 1 HIVE has been distributed proportionally to the previous days' winners who are also active on D.Buzz. 💰

• @jfang003 gets 0.700 HIVE
• @eturnerx-dbuzz gets 0.200 HIVE
• @holovision gets 0.100 HIVE

Mentions: @ahmadmanga (@ahmadmangazap) and @eturnerx (@eturnerx-dbuzz) 🤔
Special mentions: @chrisrice and @jancharlest 🤯