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Lesson 3: Elapsed time

# Time differences example

Learn to find the difference between the times shown on two different analog clocks.  Created by Lindsay Spears.

## Want to join the conversation?

• how many second can a hour have
• there are 86400 seconds in a day
• 31,449,600 in a year
• Why do you have to go right and left for the video math?
• I'm not sure if I'm understanding you correctly, but are you asking why we have to know the difference between the clock on the right vs the clock on the left?
If so, just imagine that the clock on the left is a snapshot of the clock, and then some time later you take another snapshot of the clock and that is the clock on the right. Then you have to figure out how much time passed (elapsed) from one snapshot to the next.
• Jordyn left her house for school at she stayed at school for 7 hours what time did she get home.
• i leave school at so i really want that school period,i go to a charter school so it's like their trying to make us perfect.
• There are 86,400 seconds a day.
• 1440 minutes in one day
• how do you know what time it is in a clock.
• The little tick marks, the ones in the middle show the time, and the outer ones with a bit more bold and longer are 5's in minutes, each meaning an hour, that help a bit?
• I just wanted to ask milliseconds does a hour have ?
• Interesting question! There are 60 minutes in an hour, 60 seconds in a minute, and 1,000 milliseconds in a second.
So there are 60x60x1,000 = 3,600,000 milliseconds in an hour.
• how many seconds are in a light year?
• There is no answer for that. Seconds are a unit of time, but light years, despite the misleading name, is actually a unit of distance. It is the speed of light (299,792,458 meters per second) going for a whole year (31,536,000 seconds).

It is equal to approximately 9,454,254,955,488,000 (9.4 quadrillion) meters, or 5,875,857,647,910 (5.8 trillion) miles.
• hello how much hours are in a year
• Assume a year has 365 days.

1 yr = 365 d
1 d = 24 hr

Hence, 1 year has 1 * 365 * 24 = 8760 hours.