Q&A - PSLE Science

[meimeitan]

Hi! starlight1968sg


thanks.

Another question is "Does an object lying on the ground have gravitational potential energy?"

Your prompt reply helps me a lot. thanks.

meimeitan

[starlight1968sg]

meimeitan:

Hi! starlight1968sg

thanks.
Another question is \"Does an object lying on the ground have gravitational potential energy?\"
Your prompt reply helps me a lot. thanks.
meimeitan

I can't answer your question directly.
According to the Sc textbooks, if you have a pendulum and is hung at a height, the kids are taught that the pendulum has max potential energy and min kinetic energy. If the pendulum is at the lowest position, then it has max kinetic energy and min potential energy. So if an object lies on the ground, it has min potential energy.

[meimeitan]

Hi! starlight1968sg


Sorry lah! My question actually is very long. If you don’t mind I type it out as follow:

Leming has a toy aeroplane lying on the ground. He turns the key a few times to wind it up. Then he puts it on the floor. Which of the following statements are true of the toy aeroplance when it is placed on the floor before release?

(a) It possesses elastic potential energy.
(b) It possesses gravitational potential energy.
Its spring possesses more elastic potential energy if the key is given more turns.
(d) The potential energy of the toy aeroplance will change to kinetic energy when it is released.

(1) A and B only
(2) A and C only
(3) A, C and D only
(4) A, B, C and D

The question is long. Sorry lah!

meimeitan

[starlight1968sg]

meimeitan:

Hi! starlight1968sg


Sorry lah! My question actually is very long. If you don't mind I type it out as follow:

Leming has a toy aeroplane lying on the ground. He turns the key a few times to wind it up. Then he puts it on the floor. Which of the following statements are true of the toy aeroplance when it is placed on the floor before release?

(a) It possesses elastic potential energy.
(b) It possesses gravitational potential energy.
(c) Its spring possesses more elastic potential energy if the key is given more turns.
(d) The potential energy of the toy aeroplance will change to kinetic energy when it is released.

(1) A and B only
(2) A and C only
(3) A, C and D only
(4) A, B, C and D

The question is long. Sorry lah!

meimeitan

Sorry I dont know the correct answer. DId the toy aeroplane fly? If it didnt, then option B would be out.
We need advice from Sc teachers or tutors here !

[tianzhu]

meimeitan:

Leming has a toy aeroplane lying on the ground. He turns the key a few times to wind it up. Then he puts it on the floor. Which of the following statements are true of the toy aeroplance when it is placed on the floor before release?

(a) It possesses elastic potential energy.
(b) It possesses gravitational potential energy.
(c) Its spring possesses more elastic potential energy if the key is given more turns.
(d) The potential energy of the toy aeroplance will change to kinetic energy when it is released.

(1) A and B only
(2) A and C only
(3) A, C and D only
(4) A, B, C and D

Hi

Gravitational potential energy ----- Any object that is above ground, hanging from something or on top of a slope has gravitational potential energy.

Elastic potential energy is the energy stored in elastic materials such as spring and rubber bands. The EPE increases as the number of turns increases.

When Leming releases the plane, the energy stored in the spring is released as kinetic energy which makes the plane fly.

Then he puts it on the floor -----This rule out option b ---- It possesses gravitational potential energy.

Option (a), (c) and (d) are correct, therefore the answer is (3)

Best wishes

[starlight1968sg]

tianzhu:

Gravitational potential energy ----- Any object that is above ground, hanging from something or on top of a slope has gravitational potential energy.

Elastic potential energy is the energy stored in elastic materials such as spring and rubber bands. The EPE increases as the number of turns increases.

When Leming releases the plane, the energy stored in the spring is released as kinetic energy which makes the plane fly.

Then he puts it on the floor -----This rule out option b ---- It possesses gravitational potential energy.

Option (a), (c) and (d) are correct, therefore the answer is (3)

Best wishes

Thanks a lot for your explanation. :celebrate:

[tianzhu]

starlight1968sg:

Thanks a lot for your explanation. :celebrate:

Hi

You're welcome.

You may wish to refer to PSLE Science Guide(MC) for more information.

Best wishes

[meimeitan]

Hi starlight1968sg and Tian Zhu


Thanks a lot for your explanation. Hope both of you always be with this thread. Really! Helps us a lot. Thanks again.

meimeitan

[starlight1968sg]

meimeitan:

Hi starlight1968sg and Tian Zhu

Thanks a lot for your explanation. Hope both of you always be with this thread. Really! Helps us a lot. Thanks again.
meimeitan

meimeitan,
I am still learning from others. Credit goes to Tian Zhu.

[meimeitan]

Hi!


Some challenging questions: he he he …

(1) A jar with grasshoppers in it in field from 8 am to 5 pm. Which of these factors of the environment would affect their survival?
a availability of food
b presence of predators
c inappropriate temperature

which is / are correct? Thanks.

(2) Which of the following occurs at evening (about 6 pm) in a plant?
a respiration begins to take place.
b photosynthesis stops completely.
c the rate of photosynthesis is lower than the rate of respiration.
d the rate of photosynthesis is the same as the rate of respiration.

thanks thanks thanks.

meimeitan