Question

What happens to the surface of a sphere whose radius is decreased by a factor of 4?

Answer 1

the surface area of a sphere is 4pi * r^2

so the radius is decreased by a factor of 4, the new radius is r/4
4pi * (r/4)^2

Answer 2

@perl he said factor of 4 - which can be r-1, r-2, or r-4. DECREASED; NOT DIVIDED

Answer 3

factor means multiplication

Answer 4

if they want subtraction it would just decrease by some number

Answer 5

Wait a sec

Answer 6

decreased by a factor doesn't mean multiplication -_-

Answer 7

the SA can be 4pi x (r-1)^2, 4pi x (r-2)^2, or 4pi x (r-4)^2

Answer 8

increase by factor = multiplication
decrease by factor = division

Answer 9

lucky is wrong,
the answer is, the surface area decreases by a factor of 16

Answer 10

Imagine that you are blowing bubbles with bubble gum and you blow a perfect sphere with a 4 inch radius. What would the surface area of your bubble be?



Over time, your perfect gum bubble will shrink. What happens to the surface area of your bubble if the radius decreases by half?

First, find the new radius.

4 ÷ 2 = 2

So, your new bubble has a radius of 2 in.

Then, calculate the surface area



Let’s compare the numbers.

When the radius was 4 in, the surface area was 200.96.

When the radius was 2 in, the surface area was 50.24.

So, the surface area is the original size when the radius is decreased by . Another way to say this is that when you double the diameter of the sphere the surface area is multiplied by 4.

Answer 11

new surface area = 4pi * (r/4)^2 = 4pi *r^2 / 16 = (Old surface area) / 16

Answer 12

the surface area decreases by a factor of 16.

Answer 13

After the first sentence

Answer 14

what are the choices given?

Answer 15

What happens to the surface of a sphere whose radius is decreased by a factor of 4?


Its just 1 question

Answer 16

here read this
http://wiki.answers.com/Q/If_a_radius_of_a_sphere_increase_by_a_factor_of_4_what_does_the_factor_of_the_volume_increase

Answer 17

Ok that helps but what happens when it decreases? Or what did it decrease by a factor of?

Answer 18

then we divide instead of multiply

Answer 19

division is the inverse of multiplication

Answer 20

ok

Answer 21

So it would be...

Answer 22

so let original surface area = 4pi * r^2
Then decrease radius by a factor of 4 (divide r by 4)

new surface area = 4pi * (r/4)^2 = 4pi *r^2/ 16 = (Original surface area) / 16

so original surface area is decreased by a factor of 4^2 or 16

Answer 23

Thanks

Answer 24

if you decrease radius by a factor k , then you will decrease surface area by a factor of k^2.
Similiarly if you increase radius by a factor k then you increase surface area by a factor k^2

Answer 25

Ok got it