12. A person in a wheelchair did 70.8 J of work on the chair to get it moving from rest at the bottom of a ramp, taking 1.00 s to do so. She turned the wheel (which has a radius of 40.0 cm) one quarter turn before letting go and rolling back down. If the combined mass of her and the chair was 98.0 kg, what was her final velocity when she passed back over the bottom of the ramp?

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