With the improvement of people's living standards, cars have entered the family, and the photos of the cars bought by Xiao Ming's family illustrate this point. (1) Xiao Ming found that the appearance

With the improvement of people's living standards, cars have entered the family, and the photos of the cars bought by Xiao Ming's family illustrate this point. (1) Xiao Ming found that the appearance of the car was similar to that of the car. (1) When the car is stationary, the pressure on the ground is equal to gravity; When the car is running fast, the air velocity above the car is greater than that below the car, so the gas pressure above the car is less than that below the car, and the pressure difference between the car and the car forms an upward lift, which makes the car's pressure on the ground less than the car's gravity.

(2) The vehicle pressure on the ground F=(m+m vehicle) g = (1725kg+195kg) ×10n/kg =1.92x104n;

Vehicle pressure on the ground p = fs =1.92×104n4.0×10? 2m2=4.8× 105pa

(3) Resistance when the car is running:

f = 1 10G = 1 10× 1.92× 104n = 1.92× 103n，

The car is driving at a constant speed on the straight road.

The traction and resistance of a car are a pair of balancing forces.

F=f= 1.92× 103N

(4) Vehicle collision is often caused by inertia vehicles, which should keep the original motion state and continue to move forward when braking, and cannot stop in time. So from the physical point of view, some suggestions can be put forward: don't overspeed, keep the distance between cars, slow down and so on.

So the answer is: (1) is greater than; Less than; Less than.

(2) The vehicle pressure on the ground is 4.8× 105 Pa.

(3) The traction of this automobile engine is1.92×103 n. 。

(4) It is forbidden to overspeed; Keep the distance between cars.