Robotics Worksheet: Ultrasonic Distance Sensor
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.
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- 1.📡 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 3 seconds (in cm)?
- 2.📡 Which object is hardest for an echo sensor to notice? (a) a soft foam cushion (b) a flat wall (c) a metal door (d) a wooden box
- 3.📡 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
- 4.📡 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?
- 5.📡 A robot is 240 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)?
- 6.📡 A robot is 120 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)?
- 7.📡 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 13 seconds (in cm)?
- 8.📡 In these lessons, sound travels about how far in 1 millisecond? (a) 1 km (b) 34 cm (c) 3 cm (d) 340 cm
- 9.📡 What does an ultrasonic distance sensor send out? (a) sound too high to hear (b) bright light (c) water drops (d) radio music
- 10.📡 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
- 11.📡 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?
- 12.📡 A robot is 100 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)?
- 13.📡 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 4 seconds (in cm)?
- 14.📡 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)?
- 15.📡 A robot stops if an object is closer than 100 cm. Its distance sensor hears the echo after 6 ms (sound: about 34 cm per ms). Does the robot stop? (a) Yes (b) No
- 16.📡 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)?
- 17.📡 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)?
- 18.📡 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
- 19.📡 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
- 20.📡 Which animal finds its way by echoes, like this sensor? (a) a goldfish (b) a snail (c) a bat (d) a cow
- 21.📡 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)?
- 22.📡 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)?
- 23.📡 A robot stops if an object is closer than 30 cm. Its distance sensor hears the echo after 5 ms (sound: about 34 cm per ms). Does the robot stop? (a) Yes (b) No
- 24.📡 A robot is 160 cm from a wall and drives straight at it at 10 cm per second. How far from the wall is it after 14 seconds (in cm)?
- 25.📡 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) Yes (b) No
- 26.📡 A robot is 190 cm from a wall and drives straight at it at 5 cm per second. How far from the wall is it after 24 seconds (in cm)?
- 27.📡 A robot is 220 cm from a wall and drives straight at it at 5 cm per second. How far from the wall is it after 38 seconds (in cm)?
- 28.📡 A robot is 220 cm from a wall and drives straight at it at 5 cm per second. How far from the wall is it after 26 seconds (in cm)?
- 29.📡 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 49 seconds (in cm)?
- 30.📡 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)?
- 31.📡 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
- 32.📡 A robot is 270 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)?
- 33.📡 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)?
- 34.📡 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)?
- 35.📡 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)?
- 36.📡 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 3 seconds (in cm)?
- 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 2 seconds (in cm)?
- 38.📡 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?
- 39.📡 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?
- 40.📡 Why do we halve the echo’s total path? (a) the sensor is half (b) it goes there and back (c) to make it smaller (d) sound is slow
Answer key
- 265
- a soft foam cushion
- No
- 14
- 120
- 65
- 110
- 34 cm
- sound too high to hear
- Yes
- 18
- 40
- 220
- 68
- No
- 306
- 153
- No
- Yes
- a bat
- 17
- 85
- No
- 20
- No
- 70
- 30
- 90
- 45
- 90
- No
- 20
- 110
- 272
- 110
- 60
- 200
- 12
- 17
- it goes there and back
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