Find the radius of a circle with the given circumference. 15 ft. r =
1 answer:
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Answer:
(A) 120 mph
(B) -120 mph
(C) 12 hours 5 minutes.
Step-by-step explanation:
Given that,
New York and California are 2900 miles apart,
Both the trains A as well as B travel at an average speed of 120 mph.
Assuming that the path between the starting point in New York and the ending point in California is straight, so the given distance of 2900 miles is actually the shortest distance which is the displacement between the source and destination.
So, the given speed on the straight path is actually the velocity.
Assuming that the velocity is positive in the direction from New York towards California.
(A) So, the velocity of train A (towards California) = 120 mph.
(B) The velocity of train B (towards New York) = -120 mph.
(C) Bothy are moving towards each other, so the relative velocity between them is 120+120=240 mph, and the initial distance between them is 2900 miles.
When they meet, the displacement between them becomes zero, displacement covered= 2900-0=2900 miles.
So, the time, t, taken to cover the displacement 2900 miles with a relative velocity of 240 mph is
[as time= displacement / relative velocity]
hours
=12 hours 5 minutes.
Remark
I take it that you want to know the ratio of the radii. If this is not correct, leave a comment below my answer.
You could do this by giving the spheres a definite volume, like 1 and 8 and then solve for r for one of them and then use the other sphere to find it's radius. It is not exactly the best way, and if you are going to to a physics class you want to be doing this using cancellation.
Step One
Set up the Ratio for the volumes.
Step Two
Setup the equation for V1/V2 using the definition for a sphere. V = 4/3 pi r^3
Step Three
Cancel the 4/3 and pi on the top and bottom of the fractions on the right.
You are left with 1/8 = (r1)^3/ (r2)^3
Step Four
Take the cube root of both sides.
cube root 1/8 = 1/2
Cube root of (r1)^3 = r1
Cube root of (r2)^3 = r2
Step Five
Answer
Answer <<<<<<<
I take it that you want to know the ratio of the radii. If this is not correct, leave a comment below my answer.
You could do this by giving the spheres a definite volume, like 1 and 8 and then solve for r for one of them and then use the other sphere to find it's radius. It is not exactly the best way, and if you are going to to a physics class you want to be doing this using cancellation.
Step One
Set up the Ratio for the volumes.
Step Two
Setup the equation for V1/V2 using the definition for a sphere. V = 4/3 pi r^3
Step Three
Cancel the 4/3 and pi on the top and bottom of the fractions on the right.
You are left with 1/8 = (r1)^3/ (r2)^3
Step Four
Take the cube root of both sides.
cube root 1/8 = 1/2
Cube root of (r1)^3 = r1
Cube root of (r2)^3 = r2
Step Five
Answer