Q&A - PSLE Science

[tianzhu]

underthesea:

I don' understand why option (2) - length of the ramp is not part of the answer?

Hi underthesea

To make sure that your experiment is a fair test, you must change only one factor at a time while keeping all other variables the same.
In this particular question, the height of the books and position the toy car is released are kept constant.

Try using some books and a long ruler at home; you’ll see that you need to change the length of the ramp to change the slope.

Best wishes.

[tianzhu]

happyluckymom:

Can you pls confirm the answer again for the direction of frictional force if the wheels of a car are moving in a certain direction?

Hi happyluckymom

Is rolling friction in P6 science? You may wish to check with the science teacher.

If you are interested in rolling friction, you may follow this link.
http://webphysics.davidson.edu/faculty/dmb/py430/friction/rolling.html

Best wishes

[tianzhu]

happyluckymom:

Also need to the answer for this question:

the moe the body temperature, the higher is the heart rate. Explain why such relationship occurs.

Hi happyluckymom

Is this a complete question?

In primary science, students learnt the heart pump faster and breathing rates increase when you exercise. This a common question in primary science.

What causes the body temperature to increase? Having a fever or strenuous physical activities?There are also other conditions which may cause the body temperature to rise.

In answering this question, I’ll narrow it down to increased body temperature caused by strenuous physical activities (within PSLE science syllabus).You can explain the relationship between faster heart rates and vigorous exercise (cause body temperature to increase).You may wish to refer to PSLE Guide books and primary science textbooks as the answers are readily available in them.

Best wishes

[starlight1968sg]

tianzhu:

happyluckymom:

Also need to the answer for this question:

the moe the body temperature, the higher is the heart rate. Explain why such relationship occurs.

Hi happyluckymom

Is this a complete question?

In primary science, students learnt the heart pump faster and breathing rates increase when you exercise. This a common question in primary science.

What causes the body temperature to increase? Having a fever or strenuous physical activities?There are also other conditions which may cause the body temperature to rise.

In answering this question, I’ll narrow it down to increased body temperature caused by strenuous physical activities (within PSLE science syllabus).You can explain the relationship between faster heart rates and vigorous exercise (cause body temperature to increase).You may wish to refer to PSLE Guide books and primary science textbooks as the answers are readily available in them.

Best wishes

Our heart pump faster to produce more oxygen and energy for the various parts of the body due to exercise. And thus, heat is produced to cause a slight rise in body temperature?

[atutor2001]

During exercise, our heart pump faster to transport more oxygen to the various parts of the body so that more food will be broken down into energy through a process called cell respiration. During cell respiration, some of the chemical energy of the food is changed to heat. Therefore, the faster the rate of cell respiration is, the greater will be the amount of heat produced by the cells in our body.

[starlight1968sg]

atutor2001:

During exercise, our heart pump faster to transport more oxygen to the various parts of the body so that more food will be broken down into energy through a process called cell respiration. During cell respiration, some of the chemical energy of the food is changed to heat. Therefore, the faster the rate of cell respiration is, the greater will be the amount of heat produced by the cells in our body.

Thanks for your explanation.

Another Q:
porcelain vs styrofoam.
Both are poor conductors of heat. Which one is worse?
Thanks.

[Sun_2010]

starlight1968sg:

tianzhu:

[quote=\"happyluckymom\"]Also need to the answer for this question:

the moe the body temperature, the higher is the heart rate. Explain why such relationship occurs.

Hi happyluckymom

Is this a complete question?

In primary science, students learnt the heart pump faster and breathing rates increase when you exercise. This a common question in primary science.

What causes the body temperature to increase? Having a fever or strenuous physical activities?There are also other conditions which may cause the body temperature to rise.

In answering this question, I’ll narrow it down to increased body temperature caused by strenuous physical activities (within PSLE science syllabus).You can explain the relationship between faster heart rates and vigorous exercise (cause body temperature to increase).You may wish to refer to PSLE Guide books and primary science textbooks as the answers are readily available in them.

Best wishes

Our heart pump faster to produce more oxygen and energy for the various parts of the body due to exercise. And thus, heat is produced to cause a slight rise in body temperature?[/quote]I think the question is flawed.

It should be something like - why do we prespire when we exercise?

For if you check ur body temp after exercise it is still around 37 degree Celcius - remember we are warm blooded.

When we exercise, the heart beats faster to provide more oxygen to the muscles so that it can be used to generate more energy needed for the exercise. Part of the energy is turned into heat energy when the muscles are used in exercise. More heat is produced as we run faster and faster. This is why we feel warm while playing games or running races.
Sweating is body way of cooling the body thru evapouration to maintain the temperature as we are warm blooded animals

My 2 cents, any experts wan to shed some light

[atutor2001]

Sun_2010:

.... Part of the energy is turned into heat energy when the muscles are used in exercise.....

The source of heat energy does not come from movement of the muscles alone. In fact, during the conversion from food to energy, heat is inevitably produced during the chemical reaction, regardless of whether we need it or not, that is :

food + oxygen = water + CO2 + heat + useful energy.

In cold weather, our body will convert the food into mostly heat energy to keep us warm :

food + oxygen = water + CO2 + heat + heat (useful energy)

[atutor2001]

starlight1968sg:

Another Q:
porcelain vs styrofoam.
Both are poor conductors of heat. Which one is worse?
Thanks.

Styrofoam is worse conductor of heat than porcelain. Furthermore, there are air space in styrofoam. Air is also a very poor conductor of heat.

[starlight1968sg]

atutor2001:

Styrofoam is worse conductor of heat than porcelain. Furthermore, there are air space in styrofoam. Air is also a very poor conductor of heat.

Thanks a lot, atutor2001.