# pHYSIC

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Now let us consider the length of time that the Sun is visible. Wait until the planet is at the summer solstice (12:00am). a) How many hours of daylight are there on the summer solstice with the inclination at 45 degrees? To estimate the length of day, identify the time when the sky begins to brighten and the time just before it becomes dark. You should see stars at both the beginning time and the ending time.
b) Use the above formula for sunlight-hours and the results from the previous questions to calculate the number of sunlight-hours of daylight that one receives on the summer solstice for a planet tilted by 45 degrees. Recall that the angle factor is the fraction (or component) of the light that strikes the planet perpendicular to the surface (look at the previous two questions and think carefully about what the "angle factor" should be). Show your work for full credit.

• pHYSIC - ,

.90*17=15.3

• pHYSIC - ,

To start this question, you have to go into the interactive lab for this course. Move the earth to summer solstice, and set the angle at 45 degrees. As you move the earth and look at the time daylight starts with stars visible, you continue to move the earth as the hours in the day go on when you see the last hour of daylight. This is how you get daylight hours for all the parts of these questions and do the same for winter solstice.

Other parts of the question show how to use the degrees of the angle given to calculate the angle factor by using cosine.

After all of this, you just multiply those 2 factors to get sunlight hours. Just go into the interactive lab and actually try to do the work instead of posting this question. It should have taken no more than 10 minutes to do.

FYI .90 is the wrong angle factor.