Hi Funx3,


I know this is not the correct site for my question but I'll ask anyway. For the Singapore Chemistry and Biology Olympiads for JC students, do you know if all interested JC students can register or are places limited to those taking RA chem and RA Bio only? Thanks in advance.

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.

Hi! I’m just wondering if anyone knows where to access the list of enrichment activities that count towards the Cognitive aspect of the RD. In the handbook the pupils were given, it was mentioned that the list (in handbook) was not exhaustive and we could get the updated list in the Raffles schools’ website; I can’t seem to find it. Can anyone help? Thanks!

Dr.Daniel:

red rose:

Q1. Tom uses a stopwatch to measure the time between 2 lamp-posts on a car journey. As the car speeds up, 2 consecutive times are 1.2s and 1.0s. Later, he finds out that the lamp-posts are 30m apart.
(a) Calculate the acceleration of the car and its speed at the first lamp-post.
(b) Assuming the same acceleration as found in (a), find the time the car took to travel the 30m before the first lamp-post.

For Question 1, part a)
His speed in the middle of the first time interval is 30m/1.2s = 25 m/s.
His speed in the middle of the second time interval is 30m/1s = 30 m/s
To find the acceleration, take change in speed over change in time. The change in speed is 5m/s. The change in time is 0.6s+0.5s = 1.1s. (the amount of time between the middle of the two time intervals). The acceleration is then 5/1.1 = 4.5 m/s^2.

To get the velocity at the moment he passes the first lamp post, take 25m/s to be a final velocity 0.6s later. Use: v= u+at. Solve for u, the initial velocity at the time he passes the first lamp post.

25m/s = u + 4.5(0.6s). u = 22.3m/s

Now with this velocity for part b you can solve using one of the kinematics equations. It will become the final velocity for part b. Assume constant acceleration.

This problem is unusual for secondary level in that it involves realizing that the speed you calculate is in the middle of a time interval. It takes a while to \"see\" this. I used to teach a laboratory class at University in the USA where we did these kind of calculations for falling objects.

Your help is greatly appreciated, Dr Daniel.

If it's not too much to ask, can you help with Q2 too? Thanks and have a good day!

Hi! Wondering if anyone can help me out with these 2 upper sec Physics problems.


Q1. Tom uses a stopwatch to measure the time between 2 lamp-posts on a car journey. As the car speeds up, 2 consecutive times are 1.2s and 1.0s. Later, he finds out that the lamp-posts are 30m apart.
(a) Calculate the acceleration of the car and its speed at the first lamp-post.
(b) Assuming the same acceleration as found in (a), find the time the car took to travel the 30m before the first lamp-post.

Q2. A juggler throws a ball up in the air with initial speed of 5.00m/s from a height of 1.20m. At the instant the ball reaches its maximum height, the juggler throws up another ball with the same speed and from the same height. At what height will the balls pass each other? (g=10.0m/s2)

Thank you in advance!

Hi! Can anyone enlighten me on the RA entry tests for RI? I heard there are 2 written tests - 1 mid-year, 1 year-end plus an interview. Is the year-end test only for those who did not fare well in the mid-year one? Thanks!


Cheers!

Hi! Need to clarify something. I heard that the maximum number of RA subjects that a pupil can take is now 3, no longer 2. Is this true? Thanks!

Just to clarify some inaccuracies.

1) There are no SLs in Sec 2. Only in Sec 1 Terms 2 & 3.
2) It's not true that prefects automatically get to remain so for 4 years. Sec
2 PITs or prefects-in-training are under probation and a few every year do not get to become full-fledged prefects in Sec 3. Once you're confirmed as a Sec 3 prefect however, you will remain one till Sec 4.
3) Except for Congress, PSB and House have to re-apply on a yearly basis for renewal of membership. Most who have performed well will get to carry on.

Hope this clarifies matters. [/quote]

can u just choose to apply for interviews etc to join a leadership board in yr 2, or must you be selected or something? And how do you reapply for renewal of board membership after a year? Thanks![/quote]

For 2nd intake PB (end Y2), it is mainly through form teacher recommendation. This year however, if I'm not wrong, there were a few recommended by their CCAs. There are usually very few places left (about 5), depending on that batch .

For PSB, Congress and House, just keep a look-out on iNet for announcements to apply - in Term 3. No. of available places roughly
PSB - >30
Congress - about 5
House - <10 per house

Hope this information is useful. :celebrate:

a child:

hipomum:

[quote=\"TheHamsterLover\"]May I ask, does anyone here know how you can become a psl/prefect? I know this has sort of been answered before but can someone please please clarify? And if you're not chosen after year 1 can you still be selected in year 2 and up? Thanks!

Yes, my DD is also interested to become psl..... Can seniors here advise how one can become psl?

This is a looooong answer, and I'll start with SL first.

SLs are student leaders, and basically there're three intakes, in Sec 1 Term 2, Term 3 and Sec 2. Students hold this position for one term, and can only be an SL for a total of one term (i.e. you can only be an SL once). SLs are part of PB.

At the end of Sec 1, there will be selections for the four main leadership boards in RGS - PB, PSB, Congress and House. PB and PSB selection will be determined in a camp. All SLs will go for the camp, as will other pupils nominated by their teachers. This is the first intake. There is a second intake for both boards at the end of Sec 2. However, the difference is that PSLs have to apply for board membership after every year while Prefects hold the position till the end of Sec 4.

For Student Congress and House, there will be an interview conducted to determine admission. There are 3 intakes, at the end of Sec 1, 2 and 3 respectively. Members of these boards hold their positions till the end of Sec 4.

Other than the four main boards, there are also other leadership opportunities, for example leadership in CCA and in Class. Both have Excos and chairs and are good opportunities to develop one's leadership abilities, so you don't necessarily have to be in the four boards to hold a leadership position.[/quote]Just to clarify some inaccuracies.
1) There are no SLs in Sec 2. Only in Sec 1 Terms 2 & 3.
2) It's not true that prefects automatically get to remain so for 4 years. Sec 2 PITs or prefects-in-training are under probation and a few every year do not get to become full-fledged prefects in Sec 3. Once you're confirmed as a Sec 3 prefect however, you will remain one till Sec 4.
3) Except for Congress, PSB and House have to re-apply on a yearly basis for renewal of membership. Most who have performed well will get to carry on.

Hope this clarifies matters.

Hi! Just wondering if any one here can enlighten me about the P3 classes. Which are the top 3? Thanks!