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Using a scientific calculator to calculate values from Light-Year distance equations - Succeed in Physical Science. Also refer to physics, speed of light, velocity, miles, kilometers, seconds, Ron Kurtus, School for Champions. Copyright © Restrictions
by Ron Kurtus (29 September 2006)
A light year is the distance light travels in one year of time. You can use our scientific calculator to determine the distance of a light year in either miles or kilometers.
Questions you may have include:
- How many miles is a light-year?
- How many kilometers is a light-year?
This lesson will answer those questions. There is a mini-quiz near the end of the lesson.
To find the distance traveled, you use the equation d = vt, where
- d = distance in kilometers or miles
- v = velocity or speed in miles/year or km/year
- t = time in years
- vt is v times t
For velocity, we use the speed of light. For t, we use 1 year.
The speed of light (c) is approximately 186,000 miles per second or 299,800 kilometers per second.
Since we are talking about a light-year, we need to find the speed of light in miles/year or kilometers/year. You do that by determining how many seconds there are in a year:
- 1 minute = 60 seconds
- 1 hour = 60 minutes
- 1 day = 24 hours
- 1 year = 365 days (not counting leap years)
Therefore 1 year = 365 * 24 * 60 * 60 seconds
And 1 light-year =
- seconds in a year * 186,000 miles/second or
- seconds in a year * 299,800 km/second.
Note: Since the values of c are approximates, your value for the distance d can be rounded off. You don't need all those digits, since the outcome is also an approximate.
Help on using the calculator
Seconds in year
First find the number of seconds in a year by multiplying 365 * 24 * 60 * 60. Press = and then save it to memory (M+).
Distance in miles
Multiply (*) by the speed of light in miles per second.
Round off this number.
Distance in kilometers
Clear all (AC).
Recall memory (MR) and multiply by the speed of light in kilometers per second.
Round off this number.
You have determined the distance light travels in a year.
Reader Questions and Feedback | Where can you go from here?
Apply the techniques elsewhere
The following resources provide information on this subject:
Physical Science Resources
Top-rated books on Scientific Calculators
The calculator was developed in Macromedia Flash by Atul Dabke in India.
Mini-quiz to check your understanding
1. How many seconds are there in a year?
2. Approximately, what is a light-year in miles?
3. Approximately, what is a light-year in kilometers?
If you got all three correct, you are on your way to becoming a champion in science. If you had problems, you had better look over the material again.
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