Python Programming

Let’s try to apply what we have just discussed to our Car from earlier.

For this exercise, let us add some Wheels to our car.

Your beloved software analyst now wants to be able to influence the acceleration and deceleration speed of a car based on the resistance from its wheels.

Your task

Implement the Wheel class as depicted in the diagram. This should be quite straightforward!

Then update your Car class to take in a list of wheels as an input argument to the Car constructor. You are expecting wheels to be a list of Wheel instances.

Now, update the accelerate() and decelerate() method to reduce the given rate by a certain amount depending on the number of wheels and each wheel’s resistance. Use the formula $rate^\prime = rate - 0.5 \times \sum_{i}^{wheels} resistance_{i}$, where $resistance_{i}$ is the resistance from wheel $i$. Apologies to all engineers out there for this horrible equation - I am clearly not an automotive engineer or a physicist!

For example, if rate=5, and your car has four wheels each with resistance value 0.5, the new rate should be 5 - 0.5 * (4*0.5), which is 4. Therefore, if car.accelerate(5) is invoked, then car.speed should increase by 4. Similarly, if car.decelerate(5) is invoked, then car.speed should decrease by 4. Remember that the car.speed should not be less than 0!

Sample usage

>>> wheels = [Wheel(38, 0.5)] * 4  # 4 wheels with diameter 38 and resistance 0.5
>>> my_car = Car("Honda Civic", 2015, True, wheels)
>>> my_car.accelerate(20)
>>> print(my_car.speed)
19.0
>>> my_car.decelerate(10)
>>> print(my_car.speed)
10.0
>>> my_car.brake()
>>> print(my_car.speed)
0.0