1. Two physics students, A and B are in the weightlifting room. Student A lifts the 100-N barbell over his head 10 times in one minute. Student B lifts the 100-Newton barbell over his head 10 times in 10 seconds. a. Which student does the most work? None because both students do the same amount of work lifting the same 100N barbell 10 times. b. Which student delivers the most power and why? Explain your answers.Student B delivers the most power because he does the same amount of work in a shorter time.

▾ Part A A system of two objects has AKtot 7 J and AUnt=-3 J. = Vocals Search B N How much work is done by interaction forces? Express your answer in joules. Wint ΜΕ ΑΣΦ Submit Previous Answers Request Answer X Incorrect; Try Again; 3 attempts remaining Part B How much work is done by external forces? Express your answer in joules. Wat ΜΕ ΑΣΦ Submit Request Answer Provide Feedback msi ENTER SHIFT ? J J NO.

4. A 4.21-kg watermelon is released from rest from the roof of an 27.8-m-tall building. a. Calculate the work done by gravity on the watermelon as it falls from the roof to the ground. b. Calculate the net work done on the watermelon as it falls to the ground. Show clearly how you get your answer. Just before it hits the ground, what is the watermelon's kinetic energy? Show clearly how you get your answer. d. Just before it hits the ground, what is the watermelon's speed? (Use energy techniques to answer this.) C.

A 700 kgkg elevator accelerates upward at 1.4 m/s2m/s2 for 14 mm, starting from rest. A. How much work does gravity do on the elevator? Express your answer with the appropriate units. B. How much work does the tension in the elevator cable do on the elevator? Express your answer with the appropriate units. C.What is the elevator's kinetic energy after traveling 14 mm? Express your answer with the appropriate units.