Robotics Worksheet: Ultrasonic Distance Sensor

Robotics lesson 17: The distance sensor · Set 450 · 40 questions

Robot tip (Half the echo path): Distance (cm) = 17 × echo time (ms), because 34 cm per ms ÷ 2 for there and back. Echo time (ms) = distance × 2 ÷ 34. Distance after driving = distance now − speed × time.

1. 1.📡 A distance sensor sends a sound pulse and hears the echo 2 ms later. Sound travels about 34 cm every millisecond. How far away is the object (in cm)?
2. 2.📡 A robot is 100 cm from a wall and drives straight at it at 10 cm per second. How far from the wall is it after 9 seconds (in cm)?
3. 3.📡 A robot is 130 cm from a wall and drives straight at it at 10 cm per second. How far from the wall is it after 6 seconds (in cm)?
4. 4.📡 Why do we halve the echo’s total path? (a) to make it smaller (b) sound is slow (c) it goes there and back (d) the sensor is half
5. 5.📡 A robot is 210 cm from a wall and drives straight at it at 15 cm per second. How far from the wall is it after 11 seconds (in cm)?
6. 6.📡 A distance sensor sends a sound pulse and hears the echo 10 ms later. Sound travels about 34 cm every millisecond. How far away is the object (in cm)?
7. 7.📡 A distance sensor sends a sound pulse and hears the echo 12 ms later. Sound travels about 34 cm every millisecond. How far away is the object (in cm)?
8. 8.📡 A distance sensor sends a sound pulse and hears the echo 9 ms later. Sound travels about 34 cm every millisecond. How far away is the object (in cm)?
9. 9.📡 An object is 272 cm from a distance sensor. Sound travels about 34 cm every millisecond. After how many milliseconds does the echo come back?
10. 10.📡 A robot is 250 cm from a wall and drives straight at it at 5 cm per second. How far from the wall is it after 32 seconds (in cm)?
11. 11.📡 A robot is 270 cm from a wall and drives straight at it at 15 cm per second. How far from the wall is it after 6 seconds (in cm)?
12. 12.📡 What does an ultrasonic distance sensor send out? (a) sound too high to hear (b) water drops (c) radio music (d) bright light
13. 13.📡 In these lessons, sound travels about how far in 1 millisecond? (a) 3 cm (b) 1 km (c) 34 cm (d) 340 cm
14. 14.📡 A robot is 190 cm from a wall and drives straight at it at 10 cm per second. How far from the wall is it after 4 seconds (in cm)?
15. 15.📡 A robot stops if an object is closer than 60 cm. Its distance sensor hears the echo after 8 ms (sound: about 34 cm per ms). Does the robot stop? (a) No (b) Yes
16. 16.📡 A robot stops if an object is closer than 100 cm. Its distance sensor hears the echo after 3 ms (sound: about 34 cm per ms). Does the robot stop? (a) Yes (b) No
17. 17.📡 A robot stops if an object is closer than 30 cm. Its distance sensor hears the echo after 2 ms (sound: about 34 cm per ms). Does the robot stop? (a) Yes (b) No
18. 18.📡 A distance sensor sends a sound pulse and hears the echo 7 ms later. Sound travels about 34 cm every millisecond. How far away is the object (in cm)?
19. 19.📡 A distance sensor sends a sound pulse and hears the echo 4 ms later. Sound travels about 34 cm every millisecond. How far away is the object (in cm)?
20. 20.📡 Which object is hardest for an echo sensor to notice? (a) a metal door (b) a flat wall (c) a wooden box (d) a soft foam cushion
21. 21.📡 A robot stops if an object is closer than 60 cm. Its distance sensor hears the echo after 3 ms (sound: about 34 cm per ms). Does the robot stop? (a) No (b) Yes
22. 22.📡 A distance sensor sends a sound pulse and hears the echo 18 ms later. Sound travels about 34 cm every millisecond. How far away is the object (in cm)?
23. 23.📡 An object is 187 cm from a distance sensor. Sound travels about 34 cm every millisecond. After how many milliseconds does the echo come back?
24. 24.📡 A robot stops if an object is closer than 60 cm. Its distance sensor hears the echo after 6 ms (sound: about 34 cm per ms). Does the robot stop? (a) Yes (b) No
25. 25.📡 Which animal finds its way by echoes, like this sensor? (a) a bat (b) a cow (c) a goldfish (d) a snail
26. 26.📡 An object is 204 cm from a distance sensor. Sound travels about 34 cm every millisecond. After how many milliseconds does the echo come back?
27. 27.📡 A distance sensor sends a sound pulse and hears the echo 16 ms later. Sound travels about 34 cm every millisecond. How far away is the object (in cm)?
28. 28.📡 An object is 68 cm from a distance sensor. Sound travels about 34 cm every millisecond. After how many milliseconds does the echo come back?
29. 29.📡 An object is 289 cm from a distance sensor. Sound travels about 34 cm every millisecond. After how many milliseconds does the echo come back?
30. 30.📡 A robot is 130 cm from a wall and drives straight at it at 10 cm per second. How far from the wall is it after 2 seconds (in cm)?
31. 31.📡 A distance sensor sends a sound pulse and hears the echo 8 ms later. Sound travels about 34 cm every millisecond. How far away is the object (in cm)?
32. 32.📡 A distance sensor sends a sound pulse and hears the echo 5 ms later. Sound travels about 34 cm every millisecond. How far away is the object (in cm)?
33. 33.📡 A distance sensor sends a sound pulse and hears the echo 3 ms later. Sound travels about 34 cm every millisecond. How far away is the object (in cm)?
34. 34.📡 A robot is 150 cm from a wall and drives straight at it at 5 cm per second. How far from the wall is it after 9 seconds (in cm)?
35. 35.📡 A robot stops if an object is closer than 100 cm. Its distance sensor hears the echo after 1 ms (sound: about 34 cm per ms). Does the robot stop? (a) Yes (b) No
36. 36.📡 A robot is 230 cm from a wall and drives straight at it at 10 cm per second. How far from the wall is it after 22 seconds (in cm)?
37. 37.📡 A robot is 240 cm from a wall and drives straight at it at 20 cm per second. How far from the wall is it after 3 seconds (in cm)?
38. 38.📡 A robot stops if an object is closer than 100 cm. Its distance sensor hears the echo after 2 ms (sound: about 34 cm per ms). Does the robot stop? (a) No (b) Yes
39. 39.📡 A robot stops if an object is closer than 30 cm. Its distance sensor hears the echo after 1 ms (sound: about 34 cm per ms). Does the robot stop? (a) Yes (b) No
40. 40.📡 A distance sensor sends a sound pulse and hears the echo 11 ms later. Sound travels about 34 cm every millisecond. How far away is the object (in cm)?

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