Which of the following factors does the agricultural tractor's tyres grip depend on?
Show the correct answer
Correct answer
C. The type and condition of the road surface.
Explanation
In the photo there is a street in town after a thaw: on the right there is sign B-33 "speed limit" of 40 km/h, further on sign A-7 "give way" with the plate "STOP 100 m", and cars are coming from the opposite direction. The grip of a tractor's tyres on the roadway depends on the type and condition of the road surface - answer C.
Grip is the friction force between the tyre and the road surface. It depends most on what you are driving on - asphalt, concrete, paving blocks, cobblestones or gravel - and on the condition of that surface: dry, wet, muddy, covered with sand, leaves, snow or ice. The condition of the tread and the tyre pressure also matter. The mass of a passenger being carried (answer A) is too small compared with the mass of the tractor to matter. Engine power (answer B) decides how much driving force the engine delivers to the wheels, but does not change grip - when this force exceeds the grip, the wheels simply spin. When snow is melting, as in the photo, grip changes every few metres, so brake earlier and more gently.
Legal basis: Art. 19 para. 1 of the Road Traffic Act (Prawo o ruchu drogowym)