Lower Secondary Science

[mum_sugoku]

red rose:

Would appreciate help in the following Physics problems:

1) A 5kg block of wood is pushed with a force of 60N along a horizontal flat surface at a constant speed of 10m/s. State the frictional force acting on the wood when it is pushed with a force of 40N.
2) A 6kg bowling ball collides with a single 1.5kg bowling pin. Determine the peak acceleration of the pin if the peak acceleration of the ball during the collision was 2m/s (assume no resistive force acting on both ball and pin).

Thank you in advance.

1) If contact surface remains the same, frictional force would remain unchanged, ie 60N.

2) Assuming force acting on pin = force acting on ball, then,
m(ball)a(ball)=m(pin)a(pin),
6x2= 1.5 a(pin)
hence a(pin) = 8 m/s^2

[njcstudent]

Hi, I am an IP student in Sec 1. Can anyone please recommend any good reference books and assessment books?

[Dr.033430Daniel]

mum_sugoku:

red rose:

Would appreciate help in the following Physics problems:

1) A 5kg block of wood is pushed with a force of 60N along a horizontal flat surface at a constant speed of 10m/s. State the frictional force acting on the wood when it is pushed with a force of 40N.
2) A 6kg bowling ball collides with a single 1.5kg bowling pin. Determine the peak acceleration of the pin if the peak acceleration of the ball during the collision was 2m/s (assume no resistive force acting on both ball and pin).

Thank you in advance.

1) If contact surface remains the same, frictional force would remain unchanged, ie 60N.

2) Assuming force acting on pin = force acting on ball, then,
m(ball)a(ball)=m(pin)a(pin),
6x2= 1.5 a(pin)
hence a(pin) = 8 m/s^2

For question #1, if the block starts out moving at constant speed and the pushing force is reduced from 60N to 40N, then the force of friction will be 60N and the block will decelerate and come to rest. This is probably the way to interpret the question based on the way it reads, although it is not 100% clear.
If, on the other hand, the block is initially at rest and is pushed with a force of 40N on the same surface, the force of friction will also be 40N and the block won’t move.
I mention this because last year I saw a test where they were getting at this second point.

[Dr.033430Daniel]

njcstudent:

Hi, I am an IP student in Sec 1. Can anyone please recommend any good reference books and assessment books?

I had an njc student in Sec1 last year and they were not following a standard syllabus and were doing very hard material early on. One of their modules was called \"basic atmosphere\".
Best advice I can give is to build up your basic physics and chemistry understanding. The textbook Interactive Science for Inquiring Minds is not bad. Try to understand measurement, density, speed and then go through elements and compounds and atoms and molecules.
You will probably need a higher level book for O-Level, such as Physics Insights and Chemistry Insights as a reference for harder topics.
On assessments, The red book Lower Secondary Science by GS Cheng is good.

[mum_sugoku]

:oops: :oops: :oops:

Dr.Daniel:

mum_sugoku:

[quote=\"red rose\"]Would appreciate help in the following Physics problems:

1) A 5kg block of wood is pushed with a force of 60N along a horizontal flat surface at a constant speed of 10m/s. State the frictional force acting on the wood when it is pushed with a force of 40N.
2) A 6kg bowling ball collides with a single 1.5kg bowling pin. Determine the peak acceleration of the pin if the peak acceleration of the ball during the collision was 2m/s (assume no resistive force acting on both ball and pin).

Thank you in advance.

1) If contact surface remains the same, frictional force would remain unchanged, ie 60N.

2) Assuming force acting on pin = force acting on ball, then,
m(ball)a(ball)=m(pin)a(pin),
6x2= 1.5 a(pin)
hence a(pin) = 8 m/s^2

For question #1, if the block starts out moving at constant speed and the pushing force is reduced from 60N to 40N, then the force of friction will be 60N and the block will decelerate and come to rest. This is probably the way to interpret the question based on the way it reads, although it is not 100% clear.
If, on the other hand, the block is initially at rest and is pushed with a force of 40N on the same surface, the force of friction will also be 40N and the block won’t move.
I mention this because last year I saw a test where they were getting at this second point.[/quote]Agree --> action=reaction. (Thanks for pointing that out, frankly I've never thought of the second scenario at all :oops: )

[mum_sugoku]

Dr.Daniel:

njcstudent:

Hi, I am an IP student in Sec 1. Can anyone please recommend any good reference books and assessment books?

I had an njc student in Sec1 last year and they were not following a standard syllabus and were doing very hard material early on. One of their modules was called \"basic atmosphere\".
Best advice I can give is to build up your basic physics and chemistry understanding. The textbook Interactive Science for Inquiring Minds is not bad. Try to understand measurement, density, speed and then go through elements and compounds and atoms and molecules.
You will probably need a higher level book for O-Level, such as Physics Insights and Chemistry Insights as a reference for harder topics.
On assessments, The red book Lower Secondary Science by GS Cheng is good.

My DS is also currently a year 1 student in an IP school. Agree that their science is rather tough. Take my DS for instance, while he used to score good grades in science in his pri school, he has managed to get only 'C's and 'D's for his science assessment so far ..

[keithjes]

nono81:

Hi Parents,

My friend and I (both female in late 20s) provide the tuition three sciences separately, is like offering one-stop tuition service for secondary science to meet the demands of modular science. I tutor chem and bio while my friend is tutoring physics. We are very experienced. If you are interested, do pm me. Thanks.

My daughter in Sec 3 is looking for Bilo and Chem tutor, can I have your contact pls.

[Verysuperkiasu]

What’s the water concentration level in a typical carrot tissue?

[Verysuperkiasu]

http://i42.tinypic.com/30u6zpy.jpg\">


DS requests me to put this up

In order to know which direction the air bubble move along the capillary tube, he needs to know the water concentration in a carrot tissue. Or do u have any suggested answer?

[Dr.033430Daniel]

Verysuperkiasu:

What's the water concentration level in a typical carrot tissue?

Less than distilled water.

So the distilled water moves into the carrot tissue by osmosis.