A weightlifter works out at the gym each day. Part of her routine is to lie on her back and lift a 40 kg barbell straight up from chest height to full arm extension, a distance of 0.52 m.
How much work does the weightlifter do to lift the barbell one time?
Express your answer in joules.
W = 200 J
Correct answer is shown. Your answer 204 J was either rounded differently or used a different number of significant figures than required for this part.
Important: If you use this answer in later parts, use the full unrounded value in your calculations.
Part B
If the weightlifter does 15 repetitions a day, what total energy does she expend on lifting, assuming a typical efficiency for energy use by the body (25%)?
Express your answer in joules.
E = 1.2x10^4 J
Correct answer is shown. Your answer 12230 J was either rounded differently or used a different number of significant figures than required for this part.
Part C
How many 500 Calorie donuts can she eat a day to supply that energy?
Express your answer in donuts per day.
