Question

I think I'm finding the vertical shift wrong.

http://prntscr.com/b7ajhq

So, the amplitude = 17.5
Period = 2pi/4.5
Phase shift = n/a
vertical shift = 15+25 = 40

so my equation is

17.5sin(2pi/4.5) + 40

Whenever I try to solve for the height of 50 and how long it takes to get there, I screw something up. I'm sure I screwed something up in the equation, and it's probably the vertical shift.

Answer 1

When I solve for this, I always get 26.1408, which is definitely not one of my choices.

Answer 2

The vert shift will not be the max height

I'd suggest trying to draw a diagram... the very shift will be where the center of the ride is.

Answer 3

Yeah, I made a mistake, the vertical shift is 40, yes?

Answer 4

Not quite

Answer 5

*bottom lip starts to quiver* it's... it's not?

Answer 6

Tell me the radius of the thing.

Answer 7

wait, I lied. it's 32.5

Answer 8

Well the diameter is 35, making the radius 17.5

Answer 9

and then, to find the vertical shift, it's the maximum height - the diameter = 15

and then it's 15 + 17.5 = 32.5

making so far the equation -


17.5sin(2pi/4.5) + 32.5

Answer 10

Ohhhhhh my mistake is that I made the period 2pi/4.5 it should be 2pi/5

Answer 11

17.5sin(2pi/4.5) + 32.5

This equation is missing a variable too...

Answer 12

17.5(2pi/5 t) + 32.5

there isn't a phase shift since we're starting at the midline.

Answer 13

Keep in mind that your t will be in minutes which you'll have to convert to seconds

Answer 14

I think I 'm doing something wrong.

Answer 15

17.5(2pi/5 t) + 32.5 looks right I think

Now set it equal to 50

Answer 16

50 = 17.5 (2pi/5 t) + 32.5
19.5 = 17.5(2pi/5 t)
1.1142 = (sin2pi/5 t)
sin^-1 (1.1142) = 1.26t
t = 1.1345

1.1345(60) = 68.07

Answer 17

which is not one of my answers.

Answer 18

You did some bad arithmetic in the first to second line

Answer 19

1.1142 = (sin2pi/5 t)

this should have been a red flag. Sin or cosine can never be greater than 1...

Answer 20

Well, in that case... it's

17.5 = 17.5 (sin 2pi/5 t)
0 = (sin 2pi/5 t)
sin -1 (0) = 2pi/5t

t = 1.2566
75.39

Answer 21

Yes

sin^-1 (1.1142)
how did you even get a value for that? your calculator should say error.

Answer 22

@agent0smith I honestly, have no idea. using the script calculator on my phone.

Answer 23

I don't understand. I'm absolutely lost.

Answer 24

You already worked out the answer

Answer 25

I did?

Answer 26

oh yeah, i did. 75.39. which rounds to d = 75

Answer 27

Wait you also did bad arithmetic here too

17.5 = 17.5 (sin 2pi/5 t)
0 = (sin 2pi/5 t)

17.5/17.5 is not zero!

Answer 28

Somehow by magic you seem to have got it right, though

Answer 29

1 = sin 2pi/5t)
heheh - i'm just that magical.

Answer 30

I don't understand the second one that I have here.

At the amusement park, you decide to ride the Ferris wheel, which has a maximum height of 100 meters and a diameter of 50 meters. It takes the wheel seven minutes to make one revolution. If you start your ride at the midline and the ferris wheel rotates counter clockwise, how many seconds will it take for your seat to reach a height of 75 meters? Round the answer to the nearest second.

Answer 31

So setting this up, it should be

75 = 25(sin 2pi/7)+50 right?

Answer 32

Find the vert shift same as last time

Answer 33

75.

Answer 34

The midline is also 75m. Where you start.

You're asked how long it takes to reach 75m...

Answer 35

But why is the midline also 75 in this equation?

Answer 36

Draw or imagine it and you'll see.

Answer 37

Midline is the vert shift btw

Answer 38

so if the equation is 25sin(2pi/7) +75

then t = 2pi/7?

Answer 39

Well it takes 7 minutes to rotate right? So you're at 75 when you start, and then halfway through the ride, which takes how long?

Answer 40

So we change it to 2pi/3.5?

Answer 41

No.

The whole ride takes 7 minutes. You're at 75 when you start, and then *halfway* through the ride, which takes how long?

That's what the question is asking.

Answer 42

So I solve for half of 75...? I'm so confused

Answer 43

Read slowly. The whole ride takes 7 minutes. How long does it take to get halfway through it?

Answer 44

It'll take three and a half minutes?

Answer 45

I'm sure once I figure out the equation and solve the thing, it'll be obvious, but until then...

Answer 46

Why do you need an equation?

Answer 47

Because.... Um. I can't figure it out otherwise? It'll take 109 seconds to finish the entire ride from time = 0

Answer 48

No need for an equation.

Why 109 seconds to finish the entire ride?? The question says it takes 7minutes for one complete rotation

The question asks how long it takes to reach 75 m. We know that is where we start.

We know that we'll be at 75m again, halfway through the ride.

We know the whole rotation or ride takes 7 minutes.

Therefore... How long does half the ride take?

Answer 49

Well half of 7 is 3.5 that's all I've got.

Answer 50

That's literally the only thing that makes sense.

Answer 51

Exactly.

Answer 52

Okay, then what? Solve the equation for 2pi/3.5?

Answer 53

Is it 40 seconds?

Answer 54

You're really getting mixed up here.

Answer 55

The question is basically asking how long it takes to get halfway through the ride. You literally just answered that.

Answer 56

But my choices are 0, 10, 20, and 40 seconds?

Answer 57

Then something is off here.

At the amusement park, you decide to ride the Ferris wheel, which has a maximum height of 100 meters and a diameter of 50 meters. It takes the wheel seven minutes to make one revolution. If you start your ride at the midline and the ferris wheel rotates counter clockwise, how many seconds will it take for your seat to reach a height of 75 meters? Round the answer to the nearest second.

Or just go with zero, since.... we already went over that earlier

Answer 58

"The midline is also 75m. Where you start.

You're asked how long it takes to reach 75m...

an hour ago"

Answer 59

At the start is when t= ...?

Answer 60

That's the full thing http://prntscr.com/b7bayq

Answer 61

So don't I just go through the same process as the last equation we did?

Answer 62

No. We've already done the process and again, you don't need an equation.

We already know from earlier the midline is where you start, which is 75m. So if you START at 75m, how long does it take you to reach 75m?

Answer 63

0 seconds? since you're already there.