MIDTERM II. Problem 1. Problem 2

Transcription

1 MIDTERM II Problem 1 Problem 2

2 Problem 3 3 Problem 4

3 Problem 5 Problem 6

4 Multiple Choice Questiona 1) A rock suspended by a string weighs 5 N out of water and 3 N when submerged. What is the buoyant force on the rock? A) 8 N B) 5 N C) 3 N D) 2 N 2) The ratio of output force to input force of a hydraulic press will be equal to the ratio of the output and input piston A) diameters. B) areas. C) radii. D) all of these 3) A hydraulic press multiplies a force by 100. This multiplication is done at the expense of A) energy, which is divided by 100. B) the distance through which the force acts. C) the time through which the force acts, which is multiplied by 100. D) the mechanism providing the force. 4) The pascal is a pressure unit equal to one A) newton per square meter. B) kilogram per square meter. C) newton per square centimeter. D) kilogram per square centimeter. E) square meter per newton. 5) Increased air pressure on the surface of hot water tends to A) prevent boiling. B) promote boiling. C) Neither choice A nor choice B is true. D) Choice A and choice B are both true. 6) When liquids change to a solid state, they A) absorb energy. B) release energy. C) neither absorb nor release energy. D) both absorb and release energy. 7) When a solid is changed to a liquid state, the solid

5 A) releases energy. B) absorbs energy. C) neither releases nor absorbs energy. D) both releases and absorbs energy. 8) Cold water will warm to room temperature faster in a A) black pot. B) silver pot. C) depends more on the size of the pots than their color 9) Energy transfer by convection is primarily restricted to A) solids. B) liquids. C) gases. D) fluids. 10) The higher the temperature of an object A) the longer the wavelengths it radiates. B) the shorter the wavelengths it radiates. C) makes no difference in the wavelengths it radiates 11) Which of the following contracts when the temperature is increased? Equal volumes of A) iron. B) wood. C) ice water. D) helium. E) None of the above contract when heated. 12) When an iron ring is heated, the hole becomes A) smaller. B) larger. C) neither smaller nor larger. D) either smaller or larger, depending on the ring thickness. 13) The depth to which an inverted drinking glass must be pushed beneath the surface of water so that the volume of enclosed air is squeezed to half is A) 76 cm.

6 B) 10.3 m. C) 14.7 m. D) 20.6 m. E) 29.4 m. 14) Gas pressure inside an inflated stretched balloon is actually A) less than air pressure outside the balloon. B) equal to air pressure outside the balloon. C) greater than air pressure outside the balloon. D) impossible to determine without knowing the type of gas. 15) One liter of water has a mass of A) 1 kilogram. B) 14.7 grams. C) 500 grams. D) none of the above choices 16) The pressure at the bottom of a jug filled with water does NOT depend on A) the acceleration due to gravity. B) water density. C) the height of the liquid. D) surface area of the water. 17) The buoyant force on an object is least when the object is A) partly submerged. B) submerged near the surface. C) submerged near the bottom. D) none of these 18) The fastest moving planet in a solar system is A) the smallest planet. B) the most massive planet. C) the planet nearest the sun. D) the planet farthest from the sun. E) any planet, for they all move at the same speed. 19) An airplane flies at 40 m/s at an altitude of 50 meters. The pilot drops a heavy package which falls to the ground. Where, approximately, does the package land relative to the plane's new position? A) beneath the plane B) 400 m behind the plane C) 500 m behind the plane D) more than 500 m behind the plane

7 20) A bullet fired horizontally over level ground hits the ground in 0.5 second. If it had been fired with twice the speed in the same direction, it would have hit the ground in A) less than 0.5 s. B) more than 0.5 s. C) 0.5 s. 21) A projectile is launched at ground level an angle of 15 degrees above the horizontal and lands down range. What other projection angle for the same speed would produce the same down-range distance? A) 30 degrees B) 45 degrees C) 50 degrees D) 75 degrees E) 90 degrees 22) Half way to the center of a planet of uniform density, your weight compared to that at the surface would be A) one-quarter. B) one-half. C) three-quarters. D) the same as at the surface. E) zero. 23) If the sun somehow became twice as massive, your weight as normally measured here on Earth would A) double. B) quadruple. C) not change. 24) If the sun were twice as massive A) its pull on the Earth would double. B) the pull of the Earth on the sun would double. C) both of these D) neither of these 25) Inside a freely falling elevator, there would be no A) gravitational force on you. B) apparent weight for you. C) both of these D) none of these 26) Brownian motion has to do with the A) size of atoms. B) atomic vibrations. C) first direct measurement of atomic motion. D) random motions of atoms and molecules.

8 E) rhythmic movements of atoms in a liquid. 27) Which of the following is not a mixture? A) granite B) cake C) air D) beach sand E) None. All of the above choices are mixtures. Answer: E 28) The smallest particle of those listed below is A) a molecule. B) an atom. C) a proton. D) a neutron. E) a quark. Answer: E 29) Solid matter is mostly empty space. The reason solids don't fall through one another is because A) atoms are constantly vibrating, even at absolute zero. B) of nuclear forces. C) of gravitational forces. D) of electrical forces. 30) How many different elements are in a water molecule? A) one B) two C) three D) four E) none 31) There are about as many atoms of air in our lungs at any moment as there are breaths of air in the atmosphere of A) a large auditorium. B) a large city. C) the United States. D) the whole world. 32) An atomic mass unit (amu) is 1/12 the mass of A) an electron. B) a proton. C) a hydrogen atom. D) a carbon atom. E) a uranium atom.

9 33) Which of these atoms has the most mass? A) hydrogen B) iron C) lead D) uranium E) All have the same mass. 34) A hunter on level ground fires a bullet at an angle of 10 degrees above the horizontal while simultaneously dropping another bullet from the level of the rifle. Which bullet will hit the ground first? A) the dropped one B) the fired one C) Both hit at the same time. 35) The volume of matter comes mostly from its A) protons. B) electrons. C) neutrons 36) If two protons are removed from an oxygen nucleus, the result is A) nitrogen. B) carbon. C) helium. D) neon. E) positively charged oxygen. 37) If two protons are added to an oxygen nucleus, the result is A) heavy oxygen. B) fluorine. C) neon. D) sodium. E) nitrogen. 38) If one neutron is added to a helium nucleus, the result is A) hydrogen. B) boron. C) lithium. D) beryllium. E) helium. Answer: E 39) Which of these atoms has the greatest amount of electrical charge in its nucleus? A) helium B) carbon C) iron D) gold E) uranium

10 Answer: E 40) Doubling the thickness (diameter) of a rope will multiply its strength by A) 1/2. B) 1. C) 2. D) 3. E) 4. Answer: E An object of mass 2 kg floats motionless in a fluid of specific gravity 0.8. What is the magnitude of the buoyant force? (Use g = 10 m/s 2 ). A. 8 N B. 16 N C. 20 N D. 25 N Calculate the pressure produced by a force of 800 N acting on an area of 2.0 m Pa 2. The pressure of a gas contained in a cylinder with a movable piston is 300 Pa. The area of the piston is 0.5 m 2. Calculate the force that is exerted on the piston. 150 N 3. A swimming pool of width 9.0 m and length 24.0 m is filled with water to a depth of 3.0 m. Calculate pressure on the bottom of the pool due to the water Pa 4. What is the pressure on the side wall of the pool at the junction with the bottom of the pool in the previous problem? Pa. 5. What is the total force on the bottom of the pool due to the water in the problem 3? 6.35 x 10 6 N 6. The pressure of a gas in a cylinder with a movable piston is increased from 40.0 kpa to 60.0 kpa while the temperature of the gas is held constant. If the original volume of the gas in the cylinder was 0.9 m 3 determine the final volume of the gas after the pressure is increased m 3 7. A block of wood of mass 3.5 kg floats in water. Calculate the buoyant force on the block N 8. A floating object displaces 0.6 m 3 of water. Calculate the buoyant force on the object and the weight of the object N 9. A pipe of cross sectional area 80 cm 2 has a constriction where the area is reduced to 20 cm 2. If the velocity of the fluid in the larger area is 0.3 m / s what is the velocity of the fluid in the constricted region? 1.2 m / s 10. The pipe in the previous problem is horizontal. If the pressure in the larger area region is measured as 20 kpa what is the pressure in the constricted region? KiloPascal