Tuesday Dec 8 Exam: Questions from Chapter 7, and other material not included on previous exams: 1. When a 750 gram, spherical object, of radius 2 cm, falling vertically through air of density 1.2 kg/m3is experiencing a drag force due to air resistance of about 9 N, it is a) moving at its terminal velocity b) moving slower than its terminal velocity, and slowing down # c) moving faster than its terminal velocity, but slowing down d) moving faster than its terminal velocity, and speeding up e) moving slower than its terminal velocity, but speeding up 2. Which of the following physical properties influences the drag coefficient of an object? a) the density of the fluid through which the object moves # b) the shape of the object c) the mass of the object d) all of the above (a-c) influence the drag coefficient e) none of the above (a-c) influence the drag coefficient 3. When an asteroid of diameter 100 meters, whose mass is about 3 x 109kg, traveling through space at speed of about 9 km/s slams into our planet, it will deliver a blow whose energy is about # note: a megaton(the unit of measure of a nuclear weapon's energy) is roughly equivalent to 4 x 1015J 4. A 12 kg object, initially moving with a speed of 2.0 m/s is accelerated to 5.0 m/s while only two forces are acting on it. One of the forces performs an amount of work equal to −74 J on it. How much work was done by the other force? #
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