[单选题]
A box of mass m is pulled across a horizontal surface with a force $F$ as shown in the diagram. The coefficient of dynamic friction between the box and the surface is µ. What is the energy transferred to thermal energy while a box is moved by a distance of $d$?
A. $Fd$
B. ($F-µmg$)$d$
C. $µmgd$
D. $mgd$
参考答案: C
本题详细解析: Expianation:
Energy transferred to thermal energy will be the work done by the frictional force.
Frictional force = μ$F_N$ = μmg (where $F_N$ = mg)
