A Kite Rises Straight Up To $12.0 \mathrm{~m}$ , Where It Stops Rising and Then Starts Moving Parallel

Short Answer

A kite rises straight up to $12.0 \mathrm{~m}$ , where it stops rising and then starts moving parallel to the ground at $2.10 \mathrm{~m} / \mathrm{s}$ . How fast is the angle between the kite string and the ground changing, in rad/s, $4.00 \mathrm{~s}$ after the kite starts to move horizontally? Assume the string is perfectly straight.