Question

Blades of grass grow from the bottom, so, as growth occurs, the top of the blade moves upward. During the summer, when your lawn is growing quickly, estimate this speed, in m/s. Make this estimate from your experience noting, for instance, how often you mow the lawn and what length you trim

I have no idea what to do with this tiny bit of information?
The choices given are:
A.) 3x10^3 m/s
B.) 1x10^-13 m/s
C.) 2x10^-4 m/s
D.) 4x10^-8 m/s

Answer 1

the answer is D

Step-by-step explanation:

The first choice says that the lawn grows 3000 thousand meters per second. Not realistic.

The second choice says that the growth per week is 6x10^-8 cm with this calculation

Growth per week = speed X Time (7 days, 168 hours, 604800 seconds)

Which is so low , implying that the lawn is mowed each three years.

The third option, with same above calculation, leads to 120 cm per week. Too fast. So that leaves us with the D option.

Answer 2

D.
`4x10^(-8) (m)/(s)`

The estimation is taking a week of regular time of mow the lawn and the length is trim is about an inch.

Step-by-step explanation:

So, an inch of length have to be in meters as the problem as to.

`1 in`⇒
`2,54cm`

`2,54 cm *(1m)/(100cm)= 0,0254 m`

Now, the time is a week so in seconds is modeling:

1 week ⇒ 7 days

1 day ⇒24 hours ⇒ 7 days = 7* 24 hours = 168 hours

`168 hour *(60 minute)/(1 hour) *(60 s)/(1 minute) = 604800 s`

Finally the relation is going to be the length the lawn in a week to determinate an estimation of the speed we going to call as a 'Δ'

Δ
`= (0.0254 m)/(604800 s)= 4, 19973545 *10 ^(-8)`

Approaching:

Δ
`=4 * 10^(-8) ((m)/(s) )`