# What is a good problem?

Part of the reassessment process has students pick problems to solve that they think are good demonstrations of their understanding of the material (or the standard).

For me (as the evaluator), I can learn quite a bit about what a student thinks just based on the problem they pick to solve.  However, it seems that students really don’t want to pick problems.  They would prefer to have me just tell them what problems to solve.

OK, let’s do this.  Let’s look at some problems and see which ones are good and which ones are not so good.  In this case, it will be for the Position-Velocity-Acceleration standard.  For this standard, students should show that they understand and can use the definitions of position, velocity, and acceleration in 1 dimension.  So here are some questions.  You get to pick which one is the best.  Actually, why don’t you score them from 0-10 (11 being the best).

Problem A.

A plane has a mass of 1120 kg and is landing on a runway.  The landing speed of the plane is 50 m/s and the runway is 2140 meters long.  What is the acceleration of the plane?

Problem B.

Your car is the fastest all around.  No one can beat you.  It has an acceleration of 8.2 m/s2.  Suppose you start from a rest (because, don’t all drag racers do this).  How long would it take your awesome car to get to a speed of 55 m/s?  What is this speed in mph?  What is the average speed during this time?  How far did you go?

Problem C.

A police car starts from rest and can accelerate at 5.5 m/s2.  The police car starts accelerating as soon as a speeding car passes by with a speed of 25 m/s.  Assuming the police car has a constant acceleration and the other car has a constant speed, where does the police car catch up to the other car?

Problem D.

Can you have a hang time of over 2 seconds when jumping?

Problem E.

A rocket is in space traveling with a speed of 328 m/s.  It fires its rockets to create an acceleration of -10.7 m/s2 (slowing down).  What is the speed after 5.8 seconds?

Problem F.

no words

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