Questions asked by Lilth

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• A roller coaster car is going 27 m/s when it reaches the base of a big drop. If it got all of its speed by rolling downhill, how high was the hill where the roller coaster started?
  
• A 9 kg ball starts at the top of a 84 m high building. How much kinetic energy does it have three-quarters of the way to the ground?
  
• A heat engine with an efficiency of 30 % does 834 J of work in each cycle. How much heat must be supplied from the high-temperature source in each cycle?
  
• An engine wastes 491 J of heat while producing 670 J of work. How much heat must be coming into the engine from a hot reservoir?
  
• In one cycle, a heat engine takes in 1,148 J of heat from a high-temperature reservoir, releases some heat to a lower-temperature reservoir, and does 347 J of work. What is its efficiency?
  
• If 2,514 J of heat is put into an engine, but only 1,559 J of work is produced, how much energy is wasted by this engine?
  
• A person pushes a block 7 m with a force of 21 N. How much work was done?
  
• A person does 13 J of work moving a couch 4.1 m. How much force was used?
  
• Paul Konerko hit a 135 m grand slam in Game 2 of the World Series. He did 3,245 J of work. With what force did he hit the ball?
  
• If 77 W of power is produced in 14 seconds, how much work is done?
  
• A 353 kg roller coaster car is at the top of a 90 m high hill. How much kinetic energy does the car have when it has dropped to a height of 20 meters?
  
• A 24 kg rock is teetering on the edge of a 112 m high cliff. If the rock falls, how much kinetic energy will it have just before it hits the ground?
  
• A golfer puts 2,046 J of kinetic energy into his golf club, which has a mass of 0.6 kg. What is the speed of the golf club?
  
• A ball falls from the top of a building. The ball moves 66 m/s just before it his the ground. If the ball has 5,384 J of kinetic energy, what is its mass?
  
• A running back has 2,799 J of kinetic energy when he runs at a velocity of 5 m/s. What is the mass of the running back?
  
• A system releases 318 kJ of heat while 289 kJ of work is done on the system. What is the change in internal energy?
  
• A gas in a cylinder with a moveable piston is heated with 94 J of energy, causing the piston to rise. If the internal energy of the system increases by 30 J, how much work is done by the gas?
  
• 4,020 J of heat is added to a system while 4,922 J of work is done on the system. What is the change in internal energy?
  
• Heat is added to a system, and the system does 49 J of work. If the internal energy increases by 7 J, how much heat was added to the system?
  
• In one cycle, a heat engine takes in 810 J of heat from a high-temperature reservoir, releases some heat to a lower-temperature reservoir, and does 411 J of work. What is its efficiency?
  
• A guitar string is 6.7 m long. What is the wavelength of a third harmonic standing wave?
  
• A guitar string is 5.4 meters long. What is the wavelength of a second harmonic standing wave?
  
• A guitar string is 4.6 m long. What is the wavelength of a fourth harmonic standing wave?
  
• What is the wavelength for a third harmonic standing wave on a string with fixed ends if the two ends are 2.4 m apart?
  
• What is the wavelength of a sound wave moving at 340 m/s with a frequency of 306 Hz?
  
• How fast is a wave if its frequency is 744.5 Hz and it has a wavelength of 163.1 m?
  
• An open-ended tube is 7.8 m long. What is the wavelength of a third harmonic standing wave?
  
• A closed-ended tube is 2.8 m long. What is the wavelength of a first harmonic standing wave?
  
• What is the frequency of the second harmonic sound wave in an open-ended tube that is 4.8 m long? The speed of sound in air is 340 m/s.
  
• A heat engine with an efficiency of 17 % does 836 J of work in each cycle. How much heat must be supplied from the high-temperature source in each cycle?
  
• A fifth harmonic standing wave is set up in a closed-ended pipe that is 1.4 m long. If the frequency of the wave is 239 Hz, what is its velocity?
  
• A fourth harmonic standing wave is set up in a 3 m long guitar string. If the frequency of the wave is 191 Hz, what is its velocity?
  
• 8^n=1/495 <-Fraction Logarithmic -I need help solving for the missing number (n)?
  
• If the temperature of 20.5 g of ethanol increases from 21 °C to 74 °C, how much heat has been absorbed by the ethanol? The specific heat of ethanol is 2.44 J/g °C.
  
• Gold has a specific heat of 0.129 J/g °C. How many joules of heat energy are required to raise the temperature of 16 grams of gold from 23 °C to 94 °C?
  
• How many grams of water would require 2,153 joules of heat to raise its temperature from 44 °C to 81 °C? The specific heat of water is 4.184 J/g °C.
  
• A block of cubic zirconia is placed in water (n = 1.33). A laser beam is passed from the water through the cubic zirconia. The angle of incidence is 50 deg, and the angle of refraction is 27 degrees. What is the index of refraction of this cubic zirconia?
  
• A 10 kg car is moving at 44 m/s when it collides with a stationary 71 kg truck. The two cars interlock and move off at what speed?
  
• An open-ended pipe is 6 meters long. What is the wavelength of a first harmonic standing wave?
  
• Imagine a circuit with a 47-volt battery attached to four resistors, all in parallel: a 13-ohm resistor, a 3-ohm resistor, a 15-ohm resistor, and a 4-ohm resistor. What is the total resistance of this circuit?
  
• A 131 kg car is at rest at the top of a 39 m high hill. If the car rolls down a frictionless hill, how fast will it be moving when it reaches ground level?