# 3D Space

## 35-36 Time Rates: Lengthening of shadow and movement of its tip in 3D space

## 33-34 Time Rates: A car traveling east and airplane traveling north

**Problem 33**

From a car traveling east at 40 miles per hour, an airplane traveling horizontally north at 100 miles per hour is visible 1 mile east, 2 miles south, and 2 miles up. Find when this two will be nearest together.

## 31-32 Train in an elevated track and car in perpendicular road

**Problem 31**

An elevated train on a track 30 ft above the ground crosses a street at the rate of 20 ft/sec at the instant that a car, approaching at the rate of 30 ft/sec, is 40 ft up the street. Find how fast the train and the car separating 1 second later.