1. Ian leaves his 3rd floor apartment to pick up lunch, but when he gets outside, he realizes that he has forgotten his car keys. His wife, Jane, realizes this and opens the window to toss his keys to him. Jane tosses the keys, which have a mass of 35 grams, with an initial speed of 3.0 m/s. By the time the keys reach Ian, gravity has done +3.5 J of work to the keys, and air resistance has done -2.1 J of work to the keys. What is the speed of the car keys when they reach Ian, just before he catches them? 2. 5. After a bicyclist travels 20 km, how many rotations have the wheels made? The radius of the bicycle wheels is 0.30 m.
3. 6. A 35 kg child slides down a 5.0 m long slide as shown. As the child slides, there is a kinetic friction force between the child and the slide with a coefficient of kinetic friction of 0.20. How much work (including the sign) did the gravitational force do to the child when the child slides from the top of the slide to the bottom?

Which best represents the law of conservation of mass ?

Aball is thrown upward. at a height of 10 meters above the ground, the ball has a potential energy of 50 joules (with the potential energy equal to zero at ground level) and is moving upward with a kinetic energy of 50 joules. what is the maximum height h reached by the ball? consider air friction to be negligible. 1. h ≈ 10 m 2. h ≈ 50 m 3. h ≈ 30 m 4. h ≈ 40 m 5. h ≈ 20 m 003 10.0 points which of the two object shown below has the greatest kinetic energy? a m b 1 2 m v 2v 1. kinetic energies are the same. 2. a 3. b 4. unable to determine. 004 10.0 points tim, with mass 74.6 kg, climbs a gymnasium rope a distance of 3.1 m. the acceleration of gravity is 9.8 m/s 2 . how much potential energy does tim gain? answer in units of j. 005 10.0 points a car is moving at 64 miles per hour. the kinetic energy of that car is 5 × 105 j. how much energy does the same car have when it moves at 111 miles per hour? answer in units of j. 006 10.0 points an 102 kg man climbs up a 1 m high flight of stairs. the acceleration of gravity is 9.81 m/s 2 . w

Africtionless piston-cylinder contains 50 l of saturated liquid r-134a. the piston has a mass and an area resulting in an applied pressure of 500 kpa on the refrigerant. the refrigerant is now heated until its temperature rises to 70∘c. calculate the work (in kj) done during this process.