Robotics Worksheet: Ultrasonic Distance Sensor

Robotics lesson 17: The distance sensor · Set 256 · 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 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 2 seconds (in cm)?
2. 2.📡 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)?
3. 3.📡 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)?
4. 4.📡 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)?
5. 5.📡 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)?
6. 6.📡 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
7. 7.📡 A robot is 130 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)?
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.📡 A robot is 140 cm from a wall and drives straight at it at 5 cm per second. How far from the wall is it after 13 seconds (in cm)?
10. 10.📡 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?
11. 11.📡 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
12. 12.📡 In these lessons, sound travels about how far in 1 millisecond? (a) 3 cm (b) 340 cm (c) 1 km (d) 34 cm
13. 13.📡 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
14. 14.📡 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?
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.📡 A robot is 250 cm from a wall and drives straight at it at 20 cm per second. How far from the wall is it after 12 seconds (in cm)?
17. 17.📡 A robot is 280 cm from a wall and drives straight at it at 5 cm per second. How far from the wall is it after 19 seconds (in cm)?
18. 18.📡 A robot is 220 cm from a wall and drives straight at it at 10 cm per second. How far from the wall is it after 21 seconds (in cm)?
19. 19.📡 Which animal finds its way by echoes, like this sensor? (a) a goldfish (b) a bat (c) a cow (d) a snail
20. 20.📡 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)?
21. 21.📡 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?
22. 22.📡 A distance sensor sends a sound pulse and hears the echo 6 ms later. Sound travels about 34 cm every millisecond. How far away is the object (in cm)?
23. 23.📡 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?
24. 24.📡 A distance sensor sends a sound pulse and hears the echo 14 ms later. Sound travels about 34 cm every millisecond. How far away is the object (in cm)?
25. 25.📡 A robot is 170 cm from a wall and drives straight at it at 5 cm per second. How far from the wall is it after 11 seconds (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 2 ms (sound: about 34 cm per ms). Does the robot stop? (a) Yes (b) No
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.📡 A robot is 300 cm from a wall and drives straight at it at 15 cm per second. How far from the wall is it after 19 seconds (in cm)?
30. 30.📡 Why do we halve the echo’s total path? (a) it goes there and back (b) sound is slow (c) the sensor is half (d) to make it smaller
31. 31.📡 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)?
32. 32.📡 A robot stops if an object is closer than 30 cm. Its distance sensor hears the echo after 8 ms (sound: about 34 cm per ms). Does the robot stop? (a) Yes (b) No
33. 33.📡 A robot is 240 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)?
34. 34.📡 An object is 34 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 120 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)?
36. 36.📡 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)?
37. 37.📡 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 10 seconds (in cm)?
38. 38.📡 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)?
39. 39.📡 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?
40. 40.📡 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?

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