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Questions in physics

[Done] How does the sound pressure level (SPL) change if the distance from the sound source is doubled? A. It remains the same. B. It decreases by 6 dB. C. It decreases by 3 dB. D. It increases by 3 dB.

[Done] QUESTION 17 All electromagnetic waves travel at the speed of light which is A. 30 km/s B. 300 km/s C. 3000 km/s D. 30,000 km/s QUESTION 18 In concert halls, soft materials and carpet are used to ____ sound. A. reflect B. refract C. deflect D. absorb QUESTION 19 In order for sound waves to be transmitted over long distances within a town, they have to be converted into a/an A. microwave. B. ultraviolet ray. C. electrical current. D. electromagnetic wave. QUESTION 20 Astronauts in space use radio waves to communicate because A. there is electricity in space. B. there are no air particles in space.

[Done] The chart shows the time, initial velocity, and final velocity of three riders. | Rider | Time | Initial velocity | Final velocity | | :---------- | :----- | :--------------- | :------------- | | Gabriella | 10 sec | 55 | 32 | | Franklin | 8.5 sec | 50 | 50 | | Kendall | 6 sec | 53.2 | 67 | Which best describes the riders' final velocities? A. Gabriella is speeding up at the same rate that Kendall is slowing down. B. Gabriella is slowing down at the same rate that Kendall is speeding up. C. Gabriella and Franklin are both slowing down, and Kendall is accelerating. D. Gabriella is slowing down, and Kendall and Franklin are accelerating.

[Done] A car moving with a velocity of 20 meters/second has [tex]$1.8 \times 10^5$[/tex] joules of kinetic energy. What is the mass of the car? A. [tex]$4.6 \times 10^2$[/tex] kilograms B. [tex]$9.0 \times 10^2$[/tex] kilograms C. [tex]$1.0 \times 10^3$[/tex] kilograms D. [tex]$1.2 \times 10^3$[/tex] kilograms

[Done] Select the best answer for the question. A body is a particular amount of matter. It can be a solid, liquid, or gas. It can be described as existing in A. location and movement B. time and space. C. size and shape D. motion and force

[Done] Part D: The temperature gradient between the core of Mars and its surface is approximately 0.0003 K/m. Compare this temperature gradient to that of Earth. What can you determine about the rate at which heat moves out of Mars's core compared to Earth? Part E: How do you think Earth's large temperature gradient affects the speed of its convection currents? How would this speed change if Earth's core were cooler?

[Done] An electric device delivers a current of [tex]$15.0 A$[/tex] for 30 seconds. How many electrons flow through it?

[Done] The table shows the distances between a star and three celestial objects. Use the conversion factors to rewrite the distances in different, but equivalent, units. | Celestial Objects | Distance from the Star | |---|---| | object A | 0.000001877 pc | | object B | 30.06 AU | | object C | 778.3 million km | Conversion factors: [tex]$1 AU =1.5 \times 10^8 km$[/tex] 1 light-year [tex]$=9.5 \times 10^{12} km$[/tex] 1 parsec [tex]$=31$[/tex] trillion km, or about 3.262 light-years

[Done] An electric device delivers a current of [tex]$15.0 A$[/tex] for 30 seconds. How many electrons flow through it?

[Done] 1. What happens when it rains? Why? 2. What happens when you heat the water? Why? 3. What happens when it is dark? 4. What happens when you put the water in the freezer? 5. What happens when you heat the water?