According to the second law of thermodynamics, which is a requirement for thermal energy to flow from colder objects to hotter objects?

a. work must be done on the system.

b. thermal expansion must occur in the system.

c. radiation must alter the system.

d. convection must occur within the system.

work must be done on the system  (Option A)

Explanation:

The second law of thermodynamics is the fundamental law of nature; it states that energy can be transferred from cold objects to hot objects only, if work is done on the system. If energy is added to the system then as a result the thermal energy would increase. Second law of thermodynamics is used to determine whether a process is spontaneous or not.  Moreover,the second law of thermodynamics is also used in refrigerators.

in physics zero. in muscle fatigue could be high

the tires are rotating at 0.434 rpmlinear speed=45 m/sdiameter=0.550 mradius=0.275 mnow v= rωω= v/rω=45/0.275ω=163.6 rad/sω=163.6 rad/s (1rev/2π rad) (60s/1m)ω=1563 rpm