Which of the following is true about a combustion reaction?

a. It is an endothermic reaction.

C. CO2 and H20 are produced.

b. Oxygen must be a reactant.

d. All of the above.

A student in Denver (altitude = 1 mile = 1609 m above sea level) brings a physics book of mass 1.3 kg to the top of a ten story building of height 26 m and holds the book over her head 151 cm above the roof.

At the north magnetic pole the earth's magnetic field is vertical and has a strength of 0.62 gauss. The earth's field at the surface and further out is approximately that of a central dipole.

A vessel of 0.25 m3 capacity is filled with saturated steam at 1500 kPa. If the vessel is cooled until 25% of the steam has condensed, how much heat is transferred, and what is the final pressure?

Which best describes Savanna's error? The label at the top of the diagram should be "FM Radio," not "Cell Phone." The FM carrier waves should have different frequencies than the carrier waves, not different amplitudes.

Which energy transformation propels a marathon runner across the finish line?

How are magnetic poles and electrical charges similar? A. Their same forces repel each other, and their opposite forces attract each other. B. Their same forces attract each other, and their opposite forces repel each other. C.

As part of his meal, a workman has a cup containing a hot drink. In order to keep the drink hot whilst he eats the rest of his meal, he covers the cup, as shown in the figure. Which sources of energy loss does this action reduce? Tick two boxes.

When energy is transformed, the amount of usable energy?

If an object weighs 39.2 n on earth, what is its mass

What happens when pressure is applied to a solid.