Robotics Worksheet: Ultrasonic Distance Sensor

Robotics lesson 17: The distance sensor · Set 38 · 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 323 cm from a distance sensor. Sound travels about 34 cm every millisecond. After how many milliseconds does the echo come back?
2. 2.📡 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)?
3. 3.📡 A robot stops if an object is closer than 100 cm. Its distance sensor hears the echo after 7 ms (sound: about 34 cm per ms). Does the robot stop? (a) No (b) Yes
4. 4.📡 What does an ultrasonic distance sensor send out? (a) radio music (b) water drops (c) bright light (d) sound too high to hear
5. 5.📡 A robot stops if an object is closer than 60 cm. Its distance sensor hears the echo after 2 ms (sound: about 34 cm per ms). Does the robot stop? (a) No (b) Yes
6. 6.📡 A distance sensor sends a sound pulse and hears the echo 19 ms later. Sound travels about 34 cm every millisecond. How far away is the object (in cm)?
7. 7.📡 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
8. 8.📡 An object is 153 cm from a distance sensor. Sound travels about 34 cm every millisecond. After how many milliseconds does the echo come back?
9. 9.📡 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?
10. 10.📡 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)?
11. 11.📡 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) No (b) Yes
12. 12.📡 An object is 238 cm from a distance sensor. Sound travels about 34 cm every millisecond. After how many milliseconds does the echo come back?
13. 13.📡 A robot stops if an object is closer than 30 cm. Its distance sensor hears the echo after 3 ms (sound: about 34 cm per ms). Does the robot stop? (a) Yes (b) No
14. 14.📡 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 8 seconds (in cm)?
15. 15.📡 Which object is hardest for an echo sensor to notice? (a) a flat wall (b) a wooden box (c) a metal door (d) a soft foam cushion
16. 16.📡 In these lessons, sound travels about how far in 1 millisecond? (a) 34 cm (b) 340 cm (c) 1 km (d) 3 cm
17. 17.📡 A robot stops if an object is closer than 50 cm. Its distance sensor hears the echo after 3 ms (sound: about 34 cm per ms). Does the robot stop? (a) No (b) Yes
18. 18.📡 A robot stops if an object is closer than 100 cm. Its distance sensor hears the echo after 4 ms (sound: about 34 cm per ms). Does the robot stop? (a) Yes (b) No
19. 19.📡 An object is 136 cm from a distance sensor. Sound travels about 34 cm every millisecond. After how many milliseconds does the echo come back?
20. 20.📡 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 25 seconds (in cm)?
21. 21.📡 A robot stops if an object is closer than 50 cm. Its distance sensor hears the echo after 1 ms (sound: about 34 cm per ms). Does the robot stop? (a) No (b) Yes
22. 22.📡 Which animal finds its way by echoes, like this sensor? (a) a bat (b) a snail (c) a goldfish (d) a cow
23. 23.📡 A distance sensor sends a sound pulse and hears the echo 15 ms later. Sound travels about 34 cm every millisecond. How far away is the object (in cm)?
24. 24.📡 A robot stops if an object is closer than 100 cm. Its distance sensor hears the echo after 8 ms (sound: about 34 cm per ms). Does the robot stop? (a) Yes (b) No
25. 25.📡 An object is 102 cm from a distance sensor. Sound travels about 34 cm every millisecond. After how many milliseconds does the echo come back?
26. 26.📡 A robot stops if an object is closer than 60 cm. Its distance sensor hears the echo after 4 ms (sound: about 34 cm per ms). Does the robot stop? (a) Yes (b) No
27. 27.📡 An object is 306 cm from a distance sensor. Sound travels about 34 cm every millisecond. After how many milliseconds does the echo come back?
28. 28.📡 An object is 255 cm from a distance sensor. Sound travels about 34 cm every millisecond. After how many milliseconds does the echo come back?
29. 29.📡 Why do we halve the echo’s total path? (a) sound is slow (b) it goes there and back (c) the sensor is half (d) to make it smaller
30. 30.📡 A robot is 230 cm from a wall and drives straight at it at 20 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 13 ms later. Sound travels about 34 cm every millisecond. How far away is the object (in cm)?
32. 32.📡 A robot is 260 cm from a wall and drives straight at it at 5 cm per second. How far from the wall is it after 2 seconds (in cm)?
33. 33.📡 A robot is 140 cm from a wall and drives straight at it at 15 cm per second. How far from the wall is it after 4 seconds (in cm)?
34. 34.📡 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?
35. 35.📡 A robot is 180 cm from a wall and drives straight at it at 5 cm per second. How far from the wall is it after 12 seconds (in cm)?
36. 36.📡 A robot is 140 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)?
37. 37.📡 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)?
38. 38.📡 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 12 seconds (in cm)?
39. 39.📡 A robot is 110 cm from a wall and drives straight at it at 15 cm per second. How far from the wall is it after 4 seconds (in cm)?
40. 40.📡 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)?

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