Solution to Weekly Prized Science Hub Challenge (19 October)

1 Nov

As a kitchen utensil specialist in IQEA, Lily intends to create a cooking pot which is able to cook food at a rapid rate. She then investigates two cooking pots made of the same material. She puts water and a piece of carrot into the pots, covers them with lids, and turns on the stove.

Image

(a) Besides material of the cooking pots, which other variables should be kept constant to ensure the fairness of this experiment? Give 5 options.

ANSWER

Quote:
1. The volume of water (which is sufficient to cover the carrot)
2. The mass of carrot
3. The temperature of stove
4. The length of metal plate of stove
5. The thickness of pot

(b) Based on your hypothesis, which carrot would be cooked at a faster rate? Explain why.

ANSWER

Quote:
Carrot in Set-Up B would be cooked the fastest.
The reason is because the base of cooking pot B provides greater surface area in direct contact with metal plate of the stove. It allows cooking pot B to gain heat from the stove the fastest and helps the carrot to be cooked the fastest.

EXPLANATION

Quote:

Set-Up A has lesser surface area in direct contact with the stove due to the presence of gapson its base.

Image

COMMON MISTAKE

Quote:

Set-Up B has more surface area than Set-Up A.

:idea: Set-up B has less exposed surface area to the heat than Set-Up A does. But it has more surface area in direct contact with the stove compared to Set-Up A.

(c) However, after a while, Lily finds out that the carrots from both setups are still half-cooked. Besides increasing the hotness of stove, what can she do to increase the rate of cooking? Explain.

ANSWER #1

Quote:
By keeping the mass of carrot from each setup constant, she can chop off the carrots into smaller pieces. It aims to increase the exposed surface area of carrot with the surrounding boiling water. Thus, heat from water can be gained faster to increase the rate of carrots’ cooking.

EXPLANATION

Quote:

The differences between “surface area in direct contact with” and“exposed surface area” are :

Image

Image

ANSWER #2

Quote:
She can either use a pot which is made of better conductor of heat oruse a thinner pot. Hence, heat can be transferred from the stove to the water and carrot at a faster rate, allowing the carrot to be cooked faster.

COMMON MISTAKE

Quote:

In daily life, decreasing the volume of water may help to increase the temperature of water at a faster rate, allowing the carrot to be cooked in a shorter duration of time.

However, in this case the carrot is just nicely submerged in the water (look at the diagram above)Reducing the volume of water may not soak the carrot completely. Although the water boils faster, the carrot will not be cooked evenly.

If you need more assistance in solving the questions, please feel free to either send a private message or to post in our Facebook page: Science Hub on Facebook

Advertisements

One Response to “Solution to Weekly Prized Science Hub Challenge (19 October)”

  1. matharena November 15, 2012 at 11:52 am #

    For the latest question from Weekly Prized Science Hub Challenge, please visit this page: https://matharena.wordpress.com/weekly-science-questions/

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out / Change )

Twitter picture

You are commenting using your Twitter account. Log Out / Change )

Facebook photo

You are commenting using your Facebook account. Log Out / Change )

Google+ photo

You are commenting using your Google+ account. Log Out / Change )

Connecting to %s

%d bloggers like this: