An archer fires an arrow at a target. In doing so, the tip of the arrow and the target heat up slightly. What energy change has occurred? Also, justify the solution with an equation.
The internal energy of the arrow and the target has increased due to the emitted heat: 
.
The internal energy of the arrow and the target has increased due to the archer's work and heat: 
.
The internal energy of the arrow and target has increased due to the archer's work: 
.
The internal energy of the arrow and the target increases at the expense of the archer's work and the potential energy: 
.
The internal energy of the arrow and the target has increased at the expense of the elastic energy of the arrow: 
.
