Q&A - PSLE Science

[PSLE 2012]

chow:

Help needed for Henry Park Prelim 2012 Paper 1 Q8. Do you include the \"Lime caterpillar\" in the population of the \"Lime butterfly\"? The suggested answer includes.


Thanks in advance!

Hi

In a population adult and young are included.


For example, a frog and 10 tadpoles make up 1 population
:hi5:

[paranoid]

please help with this question :?: :imdrowning:

http://i48.tinypic.com/2j3ikwi.png\">

Thanks in advance

[vaidyanathan padmini]

I just have a doubt.please help…

Two balls are placed on top of a ramp.ball A has a greater mass than ball B.which ball reaches the ground first?

Thanks in advance

[TheCoolGuy]

Haneyi:

TheCoolGuy:

Just asking, can anyone give me tips on how to answer questions in Science Booklet B? This would help me for PSLE.


Regards,
TheCoolGuy

Hello, you can take a look at this blog. I found it very helpful. ^^
http://sciencepsle.wordpress.com/

Thanks Haneyi! :imcool:

[charsen]

Robertpattinsonidle:

answer given is 3. my answer is 1. any reasons? http://i45.tinypic.com/34o6el1.jpg\">

Option A is true.

As the it's given in the Qn, \"large amount of soil is washed away\", it is likely that they are carried to the lake and got settled at the bottom. This would definitely bring up the water level causing it to be shallow.
Option 2 is true.
option 3 is false, as less light pass through murky water.

Hence Ans 3 is correct.

[charsen]

vaidyanathan padmini:

I just have a doubt.please help......

Two balls are placed on top of a ramp.ball A has a greater mass than ball B.which ball reaches the ground first?

Thanks in advance

Ball A with greater mass will reach the ground first.
Objects with greater mass will possess higher kinectic energy and hence A will travel faster than B.

[LionelMessi3175]

vaidyanathan padmini:

I just have a doubt.please help......

Two balls are placed on top of a ramp.ball A has a greater mass than ball B.which ball reaches the ground first?

Thanks in advance

Mass is the amount of matter in a object . Does the question says that ball b has greater weight?If there is no statement about it,ball a will reach the ground first

[charsen]

ALL THE BEST TO ALL PSLE STUDENTS FOR THE SCIENCE EXAM TMRW.

[LionelMessi3175]

paranoid:

Please help with this question


A company is mindful of the impact its products have on the environment. Which of the following measures could the company take to be environmentally friendly?

A. Using materials that are biodegradable
B. Using renewable energy sources to power its plants
C. Designing products that are as energy efficient as possible
D. Designing packages that save space during transportation


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

Thanks in advance. :imdrowning:

My answer is 4

[creamyhorror]

charsen:

vaidyanathan padmini:

I just have a doubt.please help......

Two balls are placed on top of a ramp.ball A has a greater mass than ball B.which ball reaches the ground first?

Thanks in advance

Ball A with greater mass will reach the ground first.
Objects with greater mass will possess higher kinectic energy and hence A will travel faster than B.

In general, if you ignore air friction, objects dropped from the same height fall with the same acceleration, regardless of their mass. This means that objects speed up at the same rate as they fall. A more massive ball will therefore reach the ground at the same time as a lighter ball dropped from the same height. This extends to objects rolling down a slope/ramp, if you ignore friction. So I'd say that both balls reach the ground at the same time.

(The gravitational potential energy (gpe) of the more massive object is higher, and after x seconds of falling it possesses more kinetic energy than the lighter object -- but that doesn't mean it's travelling faster than the lighter object. Kinetic energy is not the same as velocity.)

Let me know if this does not agree with your textbook or teachers


For parents/advanced students: http://www.batesville.k12.in.us/physics/phynet/mechanics/RotMechanics/fall_slide_roll.htm giving the evidence. The summary quote is as follows:[quote]This result says that the linear acceleration of the object down the ramp does not depend on the object's radius or mass, but it does depend on how the mass is distributed. Therefore, all spheres have the same acceleration on the ramp[/quote]Of course, at the primary school level it's unnecessary to go into the details. Just learn that objects with different masses fall through the air and roll down ramps with the same acceleration.