The sun emits electromagnetic radiation so I think they are electromagnetic waves.
Explanation:
Can be safer and cheaper than the real world. Able to test a product or system works before building it. Can use it to find unexpected problems. Can speed things up or slow them down to see changes over long or short periods of time.
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Kinetic energy is greatest at the lowest point of a roller coaster and least at the highest point
Answer:
1000N
Explanation:
Based on force=mass*acceleration, if the acceleration is constant at 2 metres per second squared, 1,000kg*2m/s^2=2,000N of force.
If the acceleration steadily increases to 2m/s^2 in 20 seconds, take the average which is 1m/s^2 therefore force=1,000N
Lower resistivity means higher conductivity: among these materials, the best conductor is silver, therefore it must be the material with lowest resistivity among those. We can also have a look at the value of resistivity of the different materials listed in the problem, to check our answer. The resistivities of the materials are the following:
Wood:

Salt water:

Silver:

Lead:

<span>We see that the material with lowest resistivity among those is silver, therefore the correct answer is silver.</span>