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The elevator in the Washington Monument takes 75 seconds to travel 500 feet to the top...
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High School Teacher
I order to solve this problem we use: `distance = rate* time.`
In algebraic terms it is `d = rt,`
where `d = 500,`
`t = 75.`
So this gives us `500=75r.` Divide both sides by 75.
`500/75 = (75r)/75` `rArr` `6.67 = r`
Which means the rate is 6.67 feet/second. Now convert to miles per hour.
There are 5280 feet in 1 mile, and 3600 seconds in 1 hour.
Therefore we get: `(6.67 ft) / (1 sec) * (1mi) / (5280 ft) * (3600 sec) / (1 hour)`
Which yields: `5.45mph`
Posted by baxthum8 on August 27, 2013 at 12:11 AM (Answer #1)
To determine this, we would divide the distance by the time:
speed = distance/time
But, we need miles per hour. We are given feet and seconds. So, we need to convert. There are a couple of ways to convert. The easiest to explain is probably with proportions, as in:
We know that there are 5280 feet in 1 mile, so we can make a ratio of 5280 feet/1 mile. Then, with the 500 feet, we can make a proportion as:
5280 feet = 500 feet
1 mile x
And, we solve for x. We need to make sure that feet are "paired" together as such. So, x = 500/5280 = 25/264 miles
Then, we do the same for the time. 60 seconds in a minute, 60 minutes in an hour. So, 3600 seconds in an hour. So, we can make 1 hour/3600 seconds. And:
1 hour = x (seconds have to be paired together)
3600 sec 75 sec
So, here, x = 75/3600 = 1/48 hour
So, speed = distance/time = (25/264)/(1/48) = 4.55 miles per hour.
Good luck, Asian girl. I hope this helps.
Posted by steveschoen on August 27, 2013 at 12:12 AM (Answer #2)
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