P3.3.3 Detecting Position

Question 1

What type of waves do your television or radio receive to get information?

Answer 1

Radio waves

Question 2

What does GPS stand for?

Answer 2

Global Positioning System

Question 3

How many satellites does GPS use?

Answer 3

24 satellites in orbit around the Earth. They transmit radio waves.

Question 4

How does GPS work?

Answer 4

1) Calculates distance from a measurement of time
2) Radio waves travel at the speed of light, 300 000 000 m/s
3) A GPS receiver detects signals from 3 satellites. From this it can work out your position.

Question 5

What does GPS require to work?

Answer 5

It needs line of sight.

Question 6

What is line of sight?

Answer 6

There needs to be a direct line from your receiver to the satellite.

Question 7

What does radar stand for?

Answer 7

Radio detection and ranging

Question 8

How does radar work?

Answer 8

1) Radio waves bounce off metal objects
2) You can find the distance using the time the reflected radio waves takes to travel
3) For radio waves, you need to use the speed of light (300 000 000 m/s)

Question 9

How do astronomers find distances to objects in the Solar System?

Answer 9

Radar

Question 10

How do astronomers find distances to objects outside our Solar System?

Answer 10

Parallax

Question 11

How does parallax work?

Answer 11

Stars appear to be in different places in June and December. So you can use mathematics to work out how far away they are.

Question 12

Why might radar not work for objects outside our Solar System?

Answer 12

It could take too long to measure distances beyond our Solar System. You might not be able to hit the object with the radio wave.