Robotics Worksheet: Ultrasonic Distance Sensor

Robotics lesson 17: The distance sensor · Set 117 · 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.📡 An object is 221 cm from a distance sensor. Sound travels about 34 cm every millisecond. After how many milliseconds does the echo come back?
2. 2.📡 A robot is 160 cm from a wall and drives straight at it at 5 cm per second. How far from the wall is it after 17 seconds (in cm)?
3. 3.📡 A robot is 140 cm from a wall and drives straight at it at 10 cm per second. How far from the wall is it after 8 seconds (in cm)?
4. 4.📡 A robot stops if an object is closer than 30 cm. Its distance sensor hears the echo after 6 ms (sound: about 34 cm per ms). Does the robot stop? (a) Yes (b) No
5. 5.📡 Why do we halve the echo’s total path? (a) to make it smaller (b) it goes there and back (c) the sensor is half (d) sound is slow
6. 6.📡 An object is 119 cm from a distance sensor. Sound travels about 34 cm every millisecond. After how many milliseconds does the echo come back?
7. 7.📡 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)?
8. 8.📡 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?
9. 9.📡 A robot is 290 cm from a wall and drives straight at it at 20 cm per second. How far from the wall is it after 10 seconds (in cm)?
10. 10.📡 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) No (b) Yes
11. 11.📡 A robot stops if an object is closer than 50 cm. Its distance sensor hears the echo after 2 ms (sound: about 34 cm per ms). Does the robot stop? (a) Yes (b) No
12. 12.📡 A robot is 160 cm from a wall and drives straight at it at 20 cm per second. How far from the wall is it after 6 seconds (in cm)?
13. 13.📡 A robot stops if an object is closer than 30 cm. Its distance sensor hears the echo after 7 ms (sound: about 34 cm per ms). Does the robot stop? (a) No (b) Yes
14. 14.📡 A robot is 290 cm from a wall and drives straight at it at 5 cm per second. How far from the wall is it after 31 seconds (in cm)?
15. 15.📡 Which object is hardest for an echo sensor to notice? (a) a wooden box (b) a flat wall (c) a soft foam cushion (d) a metal door
16. 16.📡 Which animal finds its way by echoes, like this sensor? (a) a goldfish (b) a bat (c) a cow (d) a snail
17. 17.📡 What does an ultrasonic distance sensor send out? (a) water drops (b) bright light (c) sound too high to hear (d) radio music
18. 18.📡 An object is 323 cm from a distance sensor. Sound travels about 34 cm every millisecond. After how many milliseconds does the echo come back?
19. 19.📡 In these lessons, sound travels about how far in 1 millisecond? (a) 34 cm (b) 1 km (c) 340 cm (d) 3 cm
20. 20.📡 A distance sensor sends a sound pulse and hears the echo 20 ms later. Sound travels about 34 cm every millisecond. How far away is the object (in cm)?
21. 21.📡 A robot is 280 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)?
22. 22.📡 A robot stops if an object is closer than 50 cm. Its distance sensor hears the echo after 5 ms (sound: about 34 cm per ms). Does the robot stop? (a) No (b) Yes
23. 23.📡 An object is 85 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 50 cm. Its distance sensor hears the echo after 8 ms (sound: about 34 cm per ms). Does the robot stop? (a) No (b) Yes
25. 25.📡 A distance sensor sends a sound pulse and hears the echo 1 ms later. Sound travels about 34 cm every millisecond. How far away is the object (in cm)?
26. 26.📡 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)?
27. 27.📡 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
28. 28.📡 A robot stops if an object is closer than 100 cm. Its distance sensor hears the echo after 5 ms (sound: about 34 cm per ms). Does the robot stop? (a) Yes (b) No
29. 29.📡 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)?
30. 30.📡 A robot stops if an object is closer than 30 cm. Its distance sensor hears the echo after 4 ms (sound: about 34 cm per ms). Does the robot stop? (a) Yes (b) No
31. 31.📡 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)?
32. 32.📡 An object is 51 cm from a distance sensor. Sound travels about 34 cm every millisecond. After how many milliseconds does the echo come back?
33. 33.📡 A robot is 100 cm from a wall and drives straight at it at 5 cm per second. How far from the wall is it after 16 seconds (in cm)?
34. 34.📡 A robot is 110 cm from a wall and drives straight at it at 20 cm per second. How far from the wall is it after 1 second (in cm)?
35. 35.📡 A robot is 260 cm from a wall and drives straight at it at 10 cm per second. How far from the wall is it after 20 seconds (in cm)?
36. 36.📡 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
37. 37.📡 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
38. 38.📡 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)?
39. 39.📡 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)?
40. 40.📡 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?

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