Examination III (Chapters 6,7 and 8) NAME: TW: Question #1-20 mandatory (3 point

Question

Examination III (Chapters 6,7 and 8) NAME: TW: Question #1-20 mandatory (3 points per question) From question #21-28: Show your work step by step 1) Energy that is associated with the position or composition of an object is called A) kinetic energy. B) thermal energy. C) potential energy. D) chemical energy. (3 points) 2) Define work A) the flow of energy caused by a chemical reaction B) the flow of energy caused by a temperature difference C) the result of a force acting through a distance D) the capacity to do work E) a chemical reaction (3 points) 3) An exothermic reaction has A) a negative AH, absorbs heat from the surroundings, and feels cold to the touch. B) a positive AH, gives off heat to the surroundings, and feels warm to the touch. C) a negative ??, gives off heat to the surroundings, and feels warm to the touch. D) a positive AH, absorbs heat from the surroundings, and feels cold to the touch. E) a positive AH, absorbs heat from the surroundings, and feels warm to the touch. (3 points) 4) Which of the following is the major contributor to energy consumption? A) residential B) commercial C) transportation D) industrial E) atmospheric (3 points) 5) Calculate the kinetic energy of a 150 g baseball moving at a speed of 37. m/s (83 mph). A) 5.4 J B) 1.0 x 102J C) 5.7 x 103J D) 1.0×105 J E) 2.1 x 102J (3 poin

Explanation / Answer

1) C) Potential energy

The energy possessed by a body by virtue of its position relative to others, stresses within itself, electric charge, and other factors is called potential energy.

2) C) the result of a force acting through a distance

Work done is defined as product of the force and the distance over which the force is applied. Work is done when a force is applied to an object and the object is moved through a distance. For example, when you lift a load you are applying a force over a distance so you are doing work

3) C) a negative ?H, gives off heat to the surroundings and feels warm to the touch.

A system that releases heat to the surroundings, an exothermic reaction, has a negative ?H by convention, because the enthalpy of the products is lower than the enthalpy of the reactants of the system. The enthalpies of these reactions are less than zero, and are therefore exothermic reactions.

4)D) Industrial

5) K.E.= 1/2(mv2) ; use SI units, hence convert mass to kg

            =1/2[0.150kgx(37m/s)2

            =102.675kgm2s-2

                   =1.0 x 102 J

Hence, answer is B) 1.0 x 102 J

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