mgn investigation

8/13/2019 MGN Investigation

1/15

S

Which one is faster to

fill a swimming pool?Basil 9N


2/15

Size of the swimming pool

S 25m x 7m x 2 m = 350m3

S 2500cm x 700 cm x 200cm = 350 000 000 cm3

= 350 000 000mL


3/15

Rain


4/15

Spit


5/15

Spit

S 35mL per spit


6/15

Production of rain

S Light Rain every day (2.5 millimeters per hour)

S Last for 2 hours non-stop during day-time

S 2500cm x 700cm x( 2.5 mm/10) = 437500 cm3

S 437500 mL per hour

S 437500 x 2 = 875 000mL everyday

S 350 000 000/ 875 000= 400 days


7/15

Production of Matthew

S Drink a35mL cup of water takes around 2 seconds

S Every spit takes around 1 second

S Production rate will decrease by 40 every hour as Matthew is

getting tired , the production rate will change to normal everymorning (0:00)

S Need to rest at least 11 hours per day

S As Matthew is afraid of rain, when its raining, Matthew will stop

working. That means he can only spit for 10 hours per day.S 60 s/ 3s = 20 spits per minute

S 1200 spits per hour


8/15

S 1200 + 1160 + 1120 + 1080 + 1040 + 1000 + 960 + 920 + 880

+ 840 = 10200 spits everyday

S The general term of this sequence:120040x (n-1)

S Fastest way to calculate the summation of the sequence

(1200+840)5=10200

10200 spits x 35 mL = 357 000 mL everyday

S 350000000/357 000mL= 980.3921= 980 days


9/15

S

Raining is the faster

way to fill up theswimming pool.


10/15

S

Is it better to walk orrun in the rain?


11/15

Assumption

S As you move out of the way of one falling raindrop, you

move into the way of another. So the amount of rainhitting the top of you is constant, no matter how fast you

run.

S For both running and walking, you will also run into the

same amount of raindrop, if the time spent in the rain isthe same. Assuming there are no external factors

affecting the results, such as wind and air resistance, the

amount of wetness per second will be the same in both

scenarios.


12/15

Assumption

S If you want to get from point A to point B, you will get the

same amount of rain from the front whether you arewalking or running, assuming that the rain falls down

vertically and theres no wind.

S But if you are running, you will get less amount of rain

from the top.


13/15

Formula

S This formula will be calculated in mL because the

capacity of our hair and clothing arent large enough toabsorb liters of water.

S Total Wetness (mL)=wetness (mL) per second from the

top x time spent in the rain + wetness (mL) per second

from the front x meters travelled


14/15

Example

S Total Wetness (mL)=wetness (mL) per second from the

top x time spent in the rain + wetness (mL) per second

from the front x meters travelled

Walking RunningAnswer 170mL 120mL

Wetness(mL)per

second from the top

5mL/s 5mL/s

Time (second) spent

in rain

20s 10s

Wetness (mL) per

second from the front

7mL/s 7mL/s

Meters Travelled 10m 10m


15/15

Conclusion

S According to the analysis, if there are no factors affecting

the experiment, running is a better choice because theresult has shown that the amount wetness will be less

than for running than walking.

S Therefore, you will contact less rain by running because

the time spent in the rain is less than that of walking soyou will get less rain from the top.

mgn investigation

Documents