Answer:
A)
15 hours
B)
108 hours
C)
2074.29 miles
Step-by-step explanation:
Under the assumption the earth is a perfect circle, then in one complete rotation about its axis ( 24 hours) the Earth will cover 360 degrees or 2π radians.
A)
In every 24 hours the earth rotates through 360 degrees ( a complete rotation). We are required to determine the length of time it will take the Earth to rotate through 225 degrees. Let x be the duration it takes the earth to rotate through 225 degrees, then the following proportions hold;
(24/360) = (x/225)
solving for x;
x = (24/360) * 225 = 15 hours
B)
In 24 hours the earth rotates through an angle of 2π radians (a complete rotation) . We are required to determine the length of time it will take the Earth to rotate through 9π radians. Let x be the duration it takes the earth to rotate through 9π radians, then the following proportions hold;
(24/2π radians) = (x/9π radians)
Solving for x;
x = (24/2π radians)*9π radians = 108 hours
C)
If the diameter of the earth is 7920 miles, then in a day or 24 hours a point on the equator will rotate through a distance equal to the circumference of the Earth. Using the formula for the circumference of a circle;
circumference = 2*π*R = π*D
= 7920*3.142
= 24891.43 miles
Therefore a point on the equator covers a distance of 24891.43 miles in 24 hours. This will imply that the speed of the earth is approximately;
(24891.43miles)/(24 hours) = 1037.14 miles/hr
The distance covered by the point in 2 hours will thus be;
1037.14 * 2 = 2074.29 miles
Answer:
large = 18 3/4 = 18.75
small = 13/2 = 6 1/2 = 6.5
Step-by-step explanation:
Let l = the weight of large boxes
s = weight of small boxes
2 large and 3 small weights 57
2l+3s = 57
6 large and 5 small wights 145
6l+5s = 145
Multiply the first equation by 3
3(2l+3s) = 57*3
6l +9s =171
Subtract the second equation
6l +9s =171
-6l -5s = -145
-----------------------
4s =26
Divide each side by 4
4s/4 = 26/4
s = 26/4 = 13/2
Substitute this into the first equation
2l +3s = 57
2l + 3(13/2) =57
Multiply by 2 to get rid of the fractions
2(2l + 3(13/2)) =57*2
4l + 39 = 114
Subtract 39 from each side
4l +39-39 = 114-39
4l =75
Divide by 4
4l/4 = 75/4
l = 75/4 = 18 3/4
Answer:
x = 5
Step-by-step explanation:
6/18 = x/(20-x)
1/3 = x/(20-x) Multiply both sides by 20-x
(20-x)/3 = x Multiply both sides by 3
20-x = 3x Add x in both sides
20 = 4x Divide both sides by 4
5 = x
