Physics 171, Physics and Society Quiz 1, 1pm Thurs Sept 6, 2018

Transcription

1 Quiz 1, 1pm Thurs Sept 6, Which of the following are units of energy? (a) kilogram (b) liter (c) kilowatt (d) Watt-hour 2. The fundamental reason why gasoline is so widely used is (a) it explodes when shaken sufficiently strongly (b) it can be directly pumped out of oil shale rocks (c) there is a lot of energy per gram in gasoline (d) it is safe to handle and ingest 3. Maria is riding her bicycle on a flat road. Then she squeezes the brakes and comes to a halt. Once that process is complete, the kinetic energy of Maria and her bicycle has mostly been converted to (a) potential energy (b) thermal energy (c) electrical energy (d) nuclear energy 4. When we say sugar contains about 4 Cal per gram, we mean (a) it takes that much energy to vaporize a gram of sugar (b) that is the energy released when a gram of sugar is dissolved in water (c) that is the amount of useful work a human body can do using the energy from a gram of sugar (d) that is the energy released when sugar is burned to CO 2 and H 2 O 5. The energy density of gasoline is about 10 Calories (or Watt-hours) per gram. A full tank of gas costs $50, and contains about 50 kg of gasoline. To within 20% accuracy, what is the cost of the energy in gasoline? (a) 10 /kwh (b) 50 /kwh (c) $2.50/kWh (d) $5/kWh

2 Quiz 2 1pm Thurs Sept 13, A hybrid car (like a Toyota Prius) (a) can drive a shorter distance on one tankful of gasoline than a regular gasoline car (b) uses Hydrogen to store energy (c) needs to be plugged in to an electrical outlet to recharge its battery (d) has an electric motor and a gasoline engine 2. If you use a hydrogen powered car, are you helping to reduce net carbon emissions? (a) yes, because the car only emits water vapor (b) no, because the car emits carbon dioxide (c) it depends what energy source was used to make the hydrogen (d) it depends whether you typically make short or long journeys 3. Maria cycles uphill at 5 mi/hr and then cruises downhill at 20 mi/hr. (a) when going downhill, she has 4 times as much kinetic energy as when going uphill (b) when going downhill, she has 16 times as much kinetic energy as when going uphill (c) her kinetic energy is the same whether going downhill or uphill (d) she has less kinetic energy when she travels faster, because of wind resistance 4. How fast (to within 20%) would an object have to be traveling for its kinetic energy per gram to be the same as the chemical energy density of gasoline (10 Cal/g)? (a) 1 m s 1 (b) 100 km s 1 (c) 10 km s 1 (d) 1000 m s 1

3 Quiz 3 1pm Thurs Sept 20th, When a car crashes into a brick wall, what is a good estimate of the power of the collision? (a) The kinetic energy of the car (b) The kinetic energy of the car divided by the amount of time for which the car had been driving (c) The kinetic energy of the car divided by the mass of the car (d) The kinetic energy of the car divided by the duration of the collision 2. The power output from a car battery when it is starting a car is about (a) 100 kw (b) 100 kw/s (c) 100 kwh (d) 100 kwh/s 3. Which form of energy supplies more than 10% of the U.S. s total power needs? (a) solar (b) wind (c) coal (d) hydroelectric 4. How big an area of solar panels, of about 30% efficiency, in full sunlight, would produce the amount of power needed to supply a small town of 1000 houses, each of which uses 1 kw on average? (a) 100 m 2 (b) 10 8 m 2 (c) m 2 (d) 3000 m 2

4 Quiz 4 1pm Thurs Sept 27th, Different isotopes of the same element have (a) the same number of protons in the nucleus (b) the same number of neutrons in the nucleus (c) the same total number of neutrons plus protons (d) the same atomic mass number 2. Room temperature is roughly (to within ±5 degrees) (a) 212 K (b) 20 K (c) 290 K (d) 32 K 3. Which contains a larger amount of heat energy: one liter of water at room temperature, or two liters of ice at 0 C? (a) there is more heat energy in the one liter of water (b) there is more heat energy in the two liters of ice (c) they have the same amount of heat energy (d) it is impossible to say given this information 4. The linear expansion coefficient of Mercury (a metal which is liquid at room temperature) is per C. If we take 1 liter of mercury and heat it from 20 C to 30 C, how much (to within 20% accuracy) does the volume increase by? (a) 0.6 ml (b) 2 ml (c) ml (d) 0.2 ml

5 Quiz 5 1pm Thurs Oct 4th, If a heat pump has a coefficient of performance equal to 3, then (a) for every 1 J of work going in, 3 J of heat come out (b) for every 3 J of work going in, 1 J of heat comes out (c) of the heat energy that comes out, most of it is coming from the work that went in (d) the hot region is losing heat energy at a rate of 3 W. 2. When an atom of 19 O undergoes beta decay what element does it turn in to? (a) a different isotope of Oxygen (b) Nitrogen (c) Fluorine (d) Sulfur 3. Which of the following are part of the electromagnetic spectrum? (a) neutrons (b) beta rays (c) alpha rays (d) gamma rays 4. How many molecules are there (to within 10% accuracy) in a 2 liter bottle of soda (which is mostly water)? (a) (b) (c) (d)

6 Quiz 6 1pm Thurs Oct 25th, Where does most of the gold in the Earth s crust originally come from? (a) it was formed in hot lava when the Earth was young (b) it was created in neutron star mergers (c) it came from chemical reactions between light elements in the ocean (d) it was created in the big bang 2. In nuclear fission of 235 U, (a) Uranium nuclei split because they are hit by neutrons (b) Uranium nuclei split, emitting protons (c) Uranium nuclei merge with each other because they are hit by neutrons (d) Uranium nuclei split because they are hit by fission fragments 3. A sample of a recently-dead tree contains 10 g of 12 C. When (to within a few hundred years) will it contain g of 14 C? (a) that is the amount it contains right now (b) about 5700 years from now (c) about 8500 years from now (d) about 11,000 years from now 4. Suppose your money is in a bank account that earns compound interest at a rate of 0.5% per year. How long (to within an accuracy of few years) will it take for your savings to double? (a) 15 years (b) 55 years (c) 140 years (d) 90 years