From the top of a cliff 60 m high, the angle of depression of a boat is 30°…
Contributed by StemPy LabTry it on paper first. A hint, the key idea and the worked solution are here when you need them.
From the top of a cliff m high, the angle of depression of a boat is . The boat sails straight towards the foot of the cliff. After seconds, the angle of depression is . Find the distance moved, the speed, and the time still needed to reach the foot.
Need a reminder? The key ideaShow
For an object at a fixed height , the horizontal distance at each sighting is . The distance moved is the difference of the two distances, and speed is the distance moved divided by the time. A width is a difference of two distances along one line.
The worked solution
Have you tried it?
Work it out on paper first. It is fine to get stuck or make a mistake: that is how we learn. When you are ready, go through the solution one step at a time, and check each step against your own.
Step 1. The two distances. m, and m.
Step 2. The distance moved. m.
Step 3. The speed. m/s.
Step 4. The time left. s.
Answer: m, at m/s, with s still to go.
Discussion (0)
Log in to join the discussion.
Loading…