Final answer:
To calculate the increase in thermal energy of the block-surface system, use the equations for work, force of friction, and change in thermal energy.
Step-by-step explanation:
To calculate the increase in thermal energy of the block-surface system, we need to first calculate the work done by the girl in pulling the block. The work done can be calculated using the equation:
Work = Force × Distance × Cosθ
Where the force is the component of the girl's force in the direction of motion (horizontal direction), the distance is the distance the block is pulled, and θ is the angle between the force and the horizontal. Once the work is calculated, we can use the equation:
Work = Change in Thermal Energy
Using the given coefficient of kinetic friction, we can calculate the force of friction using the equation:
Force of Friction = Coefficient of Kinetic Friction × Normal Force
The normal force can be calculated using:
Normal Force = Mass × Acceleration due to Gravity × Cosθ
Finally, we can calculate the change in thermal energy using the equation:
Change in Thermal Energy = Work - Force of Friction × Distance
Substituting the values given in the question, we can find the increase in thermal energy of the block-surface system.