The Singapore Physics League (SPhL) is a team-based competition on physics problem-solving.

By registering for SPhL, participants agree to comply with all of rules stated below.

Should participants be judged to have breached any rules, the organisers reserve the right to impose penalties, including disqualification of the entire team.


SPhL 2021 will be held on 12 June 2021, for a duration of 4 hours, from 9 am to 1 pm (Singapore time).

The syllabus for the problems will follow the International Physics Olympiad (IPhO). Sample SPhL problems are available at this link.

Teams will be awarded points for providing the correct answers to problems, and teams will be ranked on the leaderboard according to their cumulative points.


The deadline for registration is 23 April 2021, 2359 hours.

Usernames and team names should not contain profanities or inappropriate language.

Logs of each team’s online activity on the competition portal will be kept indefinitely.

Participants are allowed complete, unrestricted reference to any resources they are legally permitted to access. This includes (non-exhaustively) your own notes, textbooks, online resources found on Google, computational software (e.g. Desmos for graph plotting or Wolfram Alpha for general mathematical operations), or programmed scripts (e.g. Python, Matlab or Wolfram Mathematica).

During the competition, any discussion of problems must be confined within the team. Communication with individuals or groups outside of a participant’s team regarding the SPhL problems is strictly prohibited for the entire duration of the competition.

Acts by teams that unfairly advantage or disadvantage other teams are not permitted.


The competition is open to all current students in Singapore, from Secondary School (or equivalent) up to Junior College (or equivalent) level.

Participants may form teams of 3, 4 or 5 members. Teams smaller than 5 are permitted but discouraged. Members of a team may be from different educational levels or different schools.

Teams will be separated into 2 different categories based on the highest level of education of all team members (as of 2021):

As an illustration, a team comprising 1 JC student and 4 secondary school students will enter in Category A, the same category that a team comprising 5 JC students will enter.

All teams will attempt the same problems, regardless of category.

Leaderboard rankings of teams will be maintained separately for each category. Winners of each category will also be awarded separately.


Problems will vary in difficulty level, but are generally arranged in order of increasing difficulty.

At any time, each team will be granted access to 4 problems to solve concurrently.

Answers to all problems will be numerical, and should be given in the units specified in the problem. The degree of precision of answers should follow, at minimum, the number of significant figures stated in the problem.

If the numerical value of a constant is given in the problem statement, you should use this value in your calculations. Otherwise, use their standard values, e.g. g = 9.81 m s-2. You may refer to this data sheet for the standard values of common constants.

Answers to each problem will be submitted separately. For multi-part problems, answers to each part will be submitted independently.

When the team submits an answer to a problem, the platform instantaneously processes it real-time and informs the team whether the answer is correct or wrong.

Teams may re-attempt problems as many times as they wish, within the time limit of the competition.

Teams can also skip problems to gain access to a new problem. Skipping a problem will incur a penalty of 1 point deducted from their total score. This penalty is imposed only once per problem, i.e. for multi-part problems, teams might gain points for some parts and then skip all remaining parts with a combined penalty of 1 point regardless of the number of parts skipped.

Teams may not make submissions for 30 seconds after submitting an answer. This is to prevent random guessing.

Each question (and question-part, for multi-part problems) will be allocated a maximum number of points obtainable for a correct answer, which will serve as an approximate indication of the problem's difficulty.

The number of points awarded for a correct submission is determined by the maximum points of the problem and the number of incorrect submissions made for that problem. Specifically, points will be awarded according to the following table:

Number of incorrect submissions prior to correct submission Points awarded*
0 100% of maximum points
1 60% of maximum points
2 40% of maximum points
3 20% of maximum points
≥ 4 1 point
* Points awarded will be rounded off to the nearest integer. However, if this calculation yields 0 points, the points awarded will be instead set to 1 point.

Half Hour Rush

Half Hour Rush (HHR) commences at 10.30 am, 1.5 hours after the start of the competition, and ends at 11 am.

When HHR begins, teams gain access to 3 sets of HHR problems: Mechanics (M), Electromagnetism (E), and Others (X). Teams will have concurrent access to 1 problem from each set.

Each set will have 4 HHR problems arranged in increasing order of difficulty.

Each HHR problem is labelled based on the set it belongs to. For instance, the first HHR problem in the Mechanics set is “M1”, the fourth problem in the Electromagnetism set is “E4”, etc.

When a team correctly answers a HHR problem, the team gains access to the next HHR problem in that same set, unless that problem is the last one in the set. This means that upon solving M1, the team gains access to M2.

The added bonus of completing HHR problems is that teams will receive double the points if they complete HHR problems in “triplets”. For instance, if a team correctly answers M1, E1, and X1 (in any order) before attempting any of the second problems from each set (i.e. M2, E2, or X2), the total points they gain from answering M1, E1 and X1 will be doubled. The same applies to subsequent problems in the sets.

From here onwards, SPhL problems that are not HHR problems will be referred to as “general problems”.

Teams will still be able to access and solve 4 general problems during the HHR period, but are encouraged to focus on the additional HHR problems during this time.

The points awarded for correctly answering HHR problems follows that of the general problems, according to the table above.

Teams can also choose to skip HHR problems with a penalty of 1 point, as with general problems.

When the HHR period is over (i.e. at 11 am), teams will still be able to submit solutions, gain points, and unlock additional HHR problems (by either solving correctly or by skipping), but will no longer reap the double point bonus from completing triplets.

Accessible HHR problems (both during and after the HHR period) will not be counted under the 4 problems that teams can access concurrently. This means that if there are outstanding unsolved HHR problems, a team may be able to access up to 7 problems, including 4 general problems and 3 HHR problems.

Scoring and Appeals

Teams can submit appeals based on issues with the problems or solutions, or based on objections to penalties imposed by the organisers.

The organisers reserve the right to update scores accordingly if an appeal is accepted.

The scores will be final and no further appeals will be entertained 24 hours after the end of the competition.