Answer:
Rolling friction is much smaller than sliding friction because Rolling friction is considerably less than sliding friction as there is no work done against the body that is rolling by the force of friction. For a body to start rolling a small amount of friction is required at the point where it rests on the other surface, else it would slide instead of roll.
Rolling Friction example: Anything with weels (cars,skateboards) or a ball rooling.
Sliding Friction example: Bicycle brakes,skinning your knee walking,writing.
The total kinetic and potential energies
Answer:
V = 3.5 x 10⁻⁶ m³/s = 3.5 cm³/s
Explanation:
The volume flow rate of the blood in the artery can be given by the following formula:

where,
V = Volume flow rate = ?
A = cross-sectional area of artery = πd²/4 = π(0.004 m)²/4 = 1.26 x 10⁻⁵ m²
v = velcoity = 0.28 m/s
Therefore,

<u>V = 3.5 x 10⁻⁶ m³/s = 3.5 cm³/s</u>