Compared to a rubber wheel, a smooth plastic wheel generally produces less friction.

• A. Less friction.
• B. More friction.
• C. The same amount of friction.
• D. Friction cannot be compared.

Answer: (A)

Friction in wheel-on-surface contact comes from energy lost when the wheel deforms and interacts with the surface. Rubber is viscoelastic and deforms a lot under load, which causes more energy to dissipate as heat and increases resistance to motion. A smooth plastic wheel is stiffer and smoother, so it deforms less and has lower interfacial shear and adhesion, leading to less friction as it rolls. So, on typical dry surfaces, a smooth plastic wheel generally experiences less friction than a rubber wheel. Conditions like lubrication, surface texture, or material softness can change this, but the general trend favors the plastic wheel having lower rolling resistance.