From sea level, a helicopter rises to an elevation of 125.8 meters. Then it descends 125.8 meters. What is the elevation of the helicopter after it descends? Explain.

Am I thinking too hard and it is just zero?

1 Answer
Stefan V.
Feb 9, 2017

The helicopter will be back at sea level.

Explanation:

You know that the helicopter starts at sea level and rises to an elevation of #"125.8 m"#, then descends #"125.8 m"#.

Since the helicopter rises #"125.8 m"# and descends #"125.8 m"#, it will find itself back at sea level, for which we can assume an elevation of #"0 m"#.

If we assume that the helicopter rises straight up and descends straight down, i.e. if its motion starts and end in the same spot, we can also say that its displacement is equal to #"0 m"#.

On the other hand, the distance covered by the helicopter will be

#"125.8 m " + " 125.8 m" = "251.6 m"#

because it covers #"125.8 m"# as it's rising and #"125.8 m"# as it's descending.

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