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Physics 1A Winter 2009: Quiz 3 Version A 1 Closed book. No work needs to be shown for multiple-choice questions. 1. A Joule is a: a. kg ! m/s3 b. kg ! m2 /s c. kg ! m2 /s3 d. kg ! m/s e. kg ! m2 /s2 <-2. A car with mass M traveling at speed V has kinetic energy KE. What is the kinetic energy of a second car that has half the mass and twice the speed of the first car? a. 0.5 KE b. 2 KE <-c. 4 KE d. 8 KE e. 0.25 KE 3. An ideal spring is used to fire a 15.0 gram pellet horizontally. The pellet is initially at rest. The spring has a spring constant of 20 N/m and is initially compressed by 7.0 cm. The kinetic energy of the pellet as it leaves the spring is: a. zero b. 2.5 !10"2 J c. 4.9 !10"2 J <-d. 9.8 !10"2 J e. 1.4J 4. A Newton is a: a. kg m/s3 b. kg/s2 c. kg m/s d. kg m/s2 <--e. kg m2/s2 5. A 20-N crate starting at rest slides down a rough 5.0-m long ramp, inclined at 25° with the horizontal. 20 J of energy is lost to friction. What will be the speed of the crate at the bottom of the incline? a. 0.98 m/s b. 1.9 m/s c. 3.2 m/s d. 4.7 m/s <-e. 6.4 m/s 6. A child slides down a water slide at an amusement park from an initial height h. The slide can be considered frictionless because of the water flowing down it. (i) Can the equation for conservation of mechanical energy be used on the child? (ii) Is the mass of the child a factor in determining the speed of the child at the bottom of the slide? (iii) If the child were to drop 2.13.09 Physics 1A Winter 2009: Quiz 3 Version A 2 down without following the curved line of the slide, would it’s speed at the bottom be faster, slower, or the same? (iv) If friction was present, would the speed of the child at the bottom be larger or smaller? a. (i) yes, (ii) no, (iii) same, (iv) smaller <-b. (i) no, (ii) yes, (iii) same, (iv) smaller c. (i) no, (ii) yes, (iii) faster, (iv) larger d. (i) yes, (ii) yes, (iii) same, (iv) smaller e. (i) yes, (ii) no, (iii) faster, (iv) smaller 7. An outfielder throws a 0.150 kg baseball at a speed of 40.0 m/s at an initial angle of 30.0o with respect to the horizontal. What is the kinetic energy of the baseball at the highest point of its motion? a. zero b. 120 J c. 30.0 J d. 52.0 J e. 90.0 J <-8. Which of the following is an example of a non–conservative force? a. The gravitational force. b. The spring force. c. The force due to friction. <-d. All of the above are non–conservative forces. e. Both choices a. and b. are examples of non–conservative forces. 9. A Watt is a: a. kg m/s3 b. kg/s2 c. kg m/s d. kg m2/s3 <-- 2.13.09