Solutions

Questions

1. Answer: Servo motors can be used to control things such as: motorized theatre props, car windows, motorized furniture, blinds, and hydraulic car jacks.
2. Answer: The direction the horn angle points.
3. Answer: Angular velocity is how fast the horn turns when it’s moving from one position to another, so when it is constant it is the change in angle over time.
4. Answer: positive

Exercises

1. Answer: Approximately 26 and 128 respectively.
2. Answer: 90°
3. Answer: Angular velocity ω = (Θf – Θi) / t
   ω = (135° – 45°)/1.5 s
   ω = 90°/1.5 s
   ω = 60°/ s
4. Answer: Angular velocity ω = (Θf – Θi) / t
   ω = (45° – 180°)/2.3 s
   ω = -135°/2.3 s
   ω ≈ -58.7°/ s

Projects

1. Solution: This script is written for the range of 0° to 45°. Any 45° span is acceptable.

from microbit import *

display.off()
pin9.set_pull(pin9.NO_PULL)
pin6.set_pull(pin6.NO_PULL)
pin16.set_analog_period(20)

value = 77

while True:
    state9 = pin9.read_digital()
    state6 = pin6.read_digital()

    if state9 is 1:
        value = value + 1
        if value > 51:
            value = 51
    if state6 is 1:
        value = value - 1
        if value < 26:
            value = 26
    
    pin16.write_analog(value)
    sleep(20)

2. Solution:

from microbit import *

display.off()
pin9.set_pull(pin9.NO_PULL)
pin6.set_pull(pin6.NO_PULL)
pin16.set_analog_period(20)

value = 77

while True:
    state9 = pin9.read_digital()
    state6 = pin6.read_digital()

    if state9 is 1:
        value = value + 1
        if value > 128:
            value = 128
    if state6 is 1:
        value = value - 2
        if value < 26:
            value = 26
    
    pin16.write_analog(value)
    sleep(20)