 A 60 kg diver jumps off a diving board upward with an initial velocity of 5 m/s. The diving board is 10 m higher than the water. What is the diver's speed when just entering the water after the dive.
 A 20 kg chair has 250 J of potential energy relative to the ground. If the chair is dropped from its position, what is its speed when it strikes the ground?
 A frictionless roller coaster with a mass of 200 kg starts 15 m above the ground with a speed of 10 m/s. When it is 5 m above the ground what is its speed?
- A man rides a bicycle that is connected to an electrical generator. If he rides as hard as he can, he can generate 500 W of power, but the generator is only 40% efficient at converting that mechanical energy to power.
- How many 100 W incandescent light bulbs can he power?
- How many 100 W rated compact fluorescent light bulbs can he power?
- A small electric motor produces a force of 5 N that moves a remote-control car 5 meters every second. How much power does the motor produce? Give your answer in watts and horsepower.
- A car engine produces 100 hp.
- How many joules per second is this?
- If the engine runs at full power for 10 minutes, how many joules of energy are used?
- One gallon of gasoline contains approximately 132 million joules per gallon of chemical potential energy. If the efficiency were 100% how long could 1 gallon of gasoline run the 100 hp engine at full power?
- A real engine is about 15% efficient so only 15% of the available chemical potential energy becomes usable horsepower from the engine. How long can the engine run on a gallon of gas given this efficiency?
- A fully-charged cell phone battery contains 20,000 joules of stored energy. If the cell phone uses 2 watts of power, how long will the battery last? Give your answer in seconds, minutes, and hours.
- In the Empire State Building Run-up, participants compete to see who can run up the 320 m Empire State Building the fastest. The current record holder, Paul Crake, who has a mass of 64 kg, covered this distance in 9 minutes and 33 seconds. How much power did he produce while doing this?
- What is the maximum power generated by a mill that is turned by a waterfall that is 15 m high and has a flow rate of 200 kg/s?
| | - Suppose you have a solar energy conversion system with a sunlight collecting area of 10 m2. On a cloudless day sunlight has an intensity of about 600 W/m2.
- How much energy is collected in 1 hour?
- A single electric light bulb uses 25 watts of power. How long could the collected energy keep the bulb lit?
- A very efficient cabin uses about 400 watts on average over 24 hours. If the solar conversion to electricity is 15% efficient, can this collector supply the average power draw for the cabin?
- A light bulb draws 100 W of power. How much current does it draw if it is connected to:
- the 120 V wall outlet?
- a 9 V battery?
- a 1.5 V battery?
- A human's “normal” body temperature is 98.6°F. What is this temperature in degrees Celsius?
- During the summer an air conditioner is set to cool the room air down to 76°F. What temperature does this correspond to in degrees Celsius?
- The hottest temperature ever recorded in the continental United States was 56.7°C. What does this correspond to in degrees Fahrenheit?
- What feels hotter, 100°F or 40°C?
- How much energy is required to raise the temperature of 200 g of water from 10°C to 20°C? (Specific heat of water is 4.18 J g−1 °C−1.)
- A lead ball with mass 0.5 kg and temperature of 0°C is placed in an insulated container holding 1 kg of water at room temperature of 20°C. At what temperature do the lead ball and water reach thermal equilibrium? (Specific heat of water is 4,180 J kg−1 °C−1. Specific heat of lead is 130 J kg−1 °C−1.)
- 100 g of water at 80°C is added to 500 g of water at 20°C. If there is no heat loss to the surroundings, then what is the final temperature of the mixture of water?
- A 0.5 kg ball of an unknown metal absorbs 5775 J of energy when it heats up from 20°C to 50°C.
- Calculate the specific heat capacity of the material.
- Look up the specific heat capacities of various metals. What metal is the ball?
- A hot, 100 g glass prism is placed in 300 milliliters of water at room temperature of 22°C, causing the temperature of the water to come to equilibrium at 25°C. What was the initial temperature of the hot glass prism? (Specific heat of glass is 664 J kg−1 °C−1.)
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