Final answer:
Friction is the force that prevents feet from slipping off footrests. Textured surfaces and the angle of the footrest also contribute to increasing friction and reducing slippage.
Step-by-step explanation:
The prevention of feet from slipping off footrests is due to friction. Friction is a force that opposes motion between two surfaces in contact. When you place your feet on a footrest, the friction between the soles of your shoes and the footrest helps to keep your feet in place.
To increase the friction and prevent slipping, textured or rough surfaces can be added to the footrest. For example, rubber treads or grips can be provided on the footrest to create more friction with the shoes, reducing the likelihood of slipping.
Additionally, the angle of the footrest can also affect the potential for slipping. With a slight incline towards the body, the force of gravity helps to keep the feet in place, enhancing stability and reducing the chances of slipping.