Final answer:
The center part of a wheel is called the hub. It is responsible for holding the wheel together and allowing it to rotate smoothly.
Step-by-step explanation:
The center part of a wheel is called the hub. The hub is the central component of a wheel, where the spokes connect and the axle passes through. It is responsible for holding the wheel together and allowing it to rotate smoothly.
For example, in a car tire, the hub is the part that attaches to the axle and supports the weight of the vehicle. The rim is the outer edge of the wheel, while the hub is located at the center.
The hub is important in determining the rotational properties of the wheel, such as its angular momentum and rotational inertia, which depend on the location of the center of mass.