Betty weighs 408 Newton. She is sitting on a playground swing seat that hangs 0.41 meter above the ground in its rest position. Her initial speed is zero and her initial height above the ground is 1.55 meter. At some later time her speed is 1.05 m/s and her height above the ground is 0.95 meter. The acceleration of gravity is 9.8 m/s2.
Find the magnitude of the work done by friction during this time?
Answer in units of J.