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.📡 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?
- 2.📡 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)?
- 3.📡 What does an ultrasonic distance sensor send out? (a) radio music (b) bright light (c) sound too high to hear (d) water drops
- 4.📡 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?
- 5.📡 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) Yes (b) No
- 6.📡 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)?
- 7.📡 An object is 340 cm from a distance sensor. Sound travels about 34 cm every millisecond. After how many milliseconds does the echo come back?
- 8.📡 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) No (b) Yes
- 9.📡 In these lessons, sound travels about how far in 1 millisecond? (a) 34 cm (b) 1 km (c) 340 cm (d) 3 cm
- 10.📡 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) No (b) Yes
- 11.📡 A robot is 180 cm from a wall and drives straight at it at 10 cm per second. How far from the wall is it after 5 seconds (in cm)?
- 12.📡 Which animal finds its way by echoes, like this sensor? (a) a snail (b) a goldfish (c) a cow (d) a bat
- 13.📡 Why do we halve the echo’s total path? (a) it goes there and back (b) to make it smaller (c) sound is slow (d) the sensor is half
- 14.📡 Which object is hardest for an echo sensor to notice? (a) a soft foam cushion (b) a wooden box (c) a flat wall (d) a metal door
- 15.📡 A robot is 210 cm from a wall and drives straight at it at 5 cm per second. How far from the wall is it after 1 second (in cm)?
- 16.📡 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)?
- 17.📡 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)?
- 18.📡 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?
- 19.📡 An object is 170 cm from a distance sensor. Sound travels about 34 cm every millisecond. After how many milliseconds does the echo come back?
- 20.📡 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) No (b) Yes
- 21.📡 A robot stops if an object is closer than 60 cm. Its distance sensor hears the echo after 1 ms (sound: about 34 cm per ms). Does the robot stop? (a) Yes (b) No
- 22.📡 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?
- 23.📡 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
- 24.📡 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)?
- 25.📡 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)?
- 26.📡 A robot is 230 cm from a wall and drives straight at it at 5 cm per second. How far from the wall is it after 21 seconds (in cm)?
- 27.📡 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?
- 28.📡 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?
- 29.📡 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)?
- 30.📡 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?
- 31.📡 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 4 seconds (in cm)?
- 32.📡 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)?
- 33.📡 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?
- 34.📡 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
- 35.📡 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)?
- 36.📡 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?
- 37.📡 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 4 seconds (in cm)?
- 38.📡 A robot is 110 cm from a wall and drives straight at it at 5 cm per second. How far from the wall is it after 5 seconds (in cm)?
- 39.📡 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)?
- 40.📡 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?
Answer key
- 5
- 17
- sound too high to hear
- 9
- No
- 187
- 20
- No
- 34 cm
- Yes
- 130
- a bat
- it goes there and back
- a soft foam cushion
- 205
- 221
- 204
- 2
- 10
- No
- Yes
- 6
- Yes
- 255
- 119
- 125
- 12
- 8
- 34
- 19
- 160
- 340
- 7
- No
- 238
- 17
- 90
- 85
- 306
- 15
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