Test and analysis: (1) Volume of gasoline consumed:
,
;
(2) The car is parked on a level road.
∴ ,
,
;
(3) ,
When the car is driving at a constant speed, P=Fv. According to the figure,
∴
When the car is driving at a constant speed, the resistance of the car during driving.
(4) Because the upper surface of the airflow guide plate is straight and the lower surface is convex, when the car is driving at a high speed, the air flowing above the airflow guide plate is slow and the pressure is high; However, the air flowing under the air deflector is faster and the pressure is smaller, which makes the pressure difference between the upper and lower air deflector form a downward force, which increases the pressure and friction of the car on the ground and improves the grip performance of the wheel. (point-to-point)
Comments: This topic examines students' mastery and application of pressure formula, density formula, power formula and balance condition of two forces. When calculating the solid pressure, pay attention to the calculation of the stress area (the contact area between four wheels and the ground), and use the power to derive the formula P=Fv for calculation.