Question

A sea turtle swims at a speed of 27 km per h. A girl swims 14 dm per s.

How much faster does the sea turtle swim than the girl in meters per minute?

1 m = 10 dm

1000 m = 1 km

Answer 1

do i i put 14/60

Answer 2

or 1.4/60

Answer 3

First think about what the question is asking for.

Answer 4

How much faster does the sea turtle swim than the girl in meters per minute?

What does that^ mean?

Answer 5

Any ideas?

Answer 6

im thinking

Answer 7

Thinking is good :-)

Answer 8

hmm compare how fast the turtle is from the girl

Answer 9

Yes, but how are you asked to compare them?

Answer 10

in meters per minute

Answer 11

Ok, so what does that mean?

Answer 12

Um to divide

Answer 13

Nope, because they ask:

"How much faster does the sea turtle swim than the girl"

That^ means they want the difference in speeds, right?

Answer 14

right

Answer 15

$$\Huge\text{ in meters per minute?}$$

Answer 16

That^ statement tells you to change the units.

Answer 17

OOOH

Answer 18

They are NOT asking for the ratio of the speeds because a ratio would not have the units of "in meters per minute?"

Answer 19

oh okay

Answer 20

Good Job, Skull! :-)

Answer 21

So change both given speeds to meters per minute and subtract.

Answer 22

Thanks @InstagramModel

Answer 23

and how do i change it 0w0

Answer 24

Have you never changed units before?

Answer 25

you know how you used to know but you just need some memory help yea thats me

Answer 26

$$\Huge 27\dfrac{km}{h}$$
$$\Huge 27\dfrac{km\dfrac{1000m}{1km}}{h}$$

Answer 27

Oops I meant convert the h to minutes.

Answer 28

i was about to say....anyways its 60 minutes in a hour

Answer 29

$$\Huge 27\dfrac{1000m}{60 min}$$

Answer 30

27000 meters

Answer 31

What about the minutes?

Answer 32

its still 60 so 27000m/60min

Answer 33

Good, now simplify.

Answer 34

2250/5

Answer 35

to remember how to convert units I use this idea, which I'll express in an example:
say we want to change km to meters
then I know I want to "multiply" km by the fraction \( \frac{meters}{km} \)
the idea is I want to multiply by a fraction with km in the bottom so that it "divides out"
I want meters up top because that is the unit I want to keep
thus
\[ 27 \ \cancel{km} \cdot \frac{1000 \ meters}{1 \ \cancel{km}} \]

Answer 36

if we have to convert (for example) km/hr to m/min
then I would do it like this:
\[ 27 \frac{\cancel{km}}{hr} \cdot \frac{1000 \ meters}{1 \ \cancel{km}} \]
then I want to get rid of the 1/hr so multiply by hr/min
\[ 27 \frac{\cancel{km}}{\cancel{hr}} \cdot \frac{1000 \ meters}{1 \ \cancel{km}} \cdot \frac{1 \
\cancel{hr}}{60 \ min}\]

Answer 37

to change dm/sec to meters/min
\[ \frac{dm}{sec} \cdot \frac{m}{dm} \cdot \frac{sec}{min} \]

see how we pick "fractions" that cancel out the dm and cancel out the sec ?
of course we need numbers
we know 60 sec = 1 min and if we divide both sides by 1 min we get
\[ \frac{60 \ sec}{1 \ min} = 1 \]
the left side is the fraction we want

they tell us
1 m = 10 dm

and we want m/dm, so using that equation, divide both sides by 10 dm to get
\[ \frac{1 \ m}{10 \ dm} =1 \]
and the left side is the conversion fraction we want.

Answer 38

putting in numbers:
\[ 14 \frac{dm}{sec} \cdot \frac{1 \ m}{10 \ dm} \cdot \frac{60 \ sec}{1 \ min} = 84 \frac{m}{min}\]

and similarly
\[ 27 \frac{km}{hr} \cdot \frac{1000 \ meters}{1 \ km} \cdot \frac{1 \
hr}{60 \ min}= \frac{27\cdot 1000}{60}\frac{m}{min}= 450 \frac{m}{min} \]

now find the difference in the two speeds.

Answer 39

im lost now

Answer 40

Following on from what skull patrol was discussing about converting the units:

a) What is the speed of the turtle in metres/min?
b) What is the speed of the girl in metres/min?