Category Archives: High School

Items appropriate for use in a high school physics course.

A2L Item 118

Goal: Hone the vector nature of electric force.

Source: UMPERG-A2LEM2

Two charges, a negative charge Q, and a positive charge q, are
positioned as shown in the diagram. What is the direction of the
electrical force on q due to Q?

Commentary:

Answer

(3) The force is attractive.

A2L Item 115

Goal: Reasoning about temperature.

Source: UMPERG-ctqpe186

Two moles of an ideal gas fill a volume of 10 liters with a pressure of
2.4 atm. The gas is thermally insulated from the surroundings. A
membrane is broken which allows the gas to expand into the new volume
which is 3 times as large as the old volume. The new temperature is …

  1. The same as before.
  2. Lower than before.
  3. Higher than before.
  4. Cannot be determined.

Commentary:

Answer

(1) Students may erroneously apply prior knowledge that gas cools as it
expands. Some will likely think that the answer cannot be determined
without more information.

A2L Item 116

Goal: Hone vector nature of electric fields

Source: UMPERG-em97Q

Two uniformly charged rods are positioned horizontally as shown. The
top rod is positively charged and the bottom rod is negatively charged.
The total electric field at the origin

  1. Is 0.
  2. Has both an x and a y component.
  3. Points totally in the i direction.
  4. Points totally in the -i direction.
  5. Points totally in the j direction.
  6. Points totally in the -j direction.

Commentary:

Answer

(6) Along the y-axis, by symmetry, the electric field due to either rod
points along the y-axis. At the origin the contribution to each rod is
the same and points down.

A2L Item 114

Goal: Problem solving with the ideal gas law

Source: UMPERG-ctqpe184

Two moles of an ideal gas fill volume V = 10 liters at pressure P = 2.4
atm. The gas is thermally insulated from the surroundings. A membrane
is broken which allows the gas to expand into the new volume which is 3
times as large as the old volume. The new pressure is:

  1. .4 atm
  2. .8 atm
  3. 1.2 atm
  4. 1.6 atm
  5. 2.4 atm
  6. None of the above
  7. Cannot be determined

Commentary:

Answer

(2) Some students may wonder about the applicability of the ideal gas
law for free expansion. Some may respond (7) thinking that since gas
cools as it expands, they do not know what the final temperature is and
cannot, therefore, use the ideal gas law.

A2L Item 111

Goal: Problem solving

Source: UMPERG-ctqpe182

What temperature reading (if any) would have the same numerical value on
both the Celcius and Fahrenheit temperature scales?

  1. 0°
  2. -40°
  3. 180°
  4. 72°
  5. -25.6°
  6. 568°
  7. None of the above
  8. Cannot be determined

Commentary:

Answer

(2) This is a standard problem useful for determining whether students
are comfortable converting between the two temperature scales.

A2L Item 103

Goal: Reason with rotational dynamics.

Source: UMPERG-ctqpe138

A spool has string wrapped around its center axle and is sitting on a
horizontal surface. If the string is pulled at an angle to the
horizontal when drawn from the bottom of the axle, the spool will

  1. roll to the right.
  2. not roll, only slip.
  3. roll to the left.
  4. cannot be determined.

Commentary:

Answer

(4) The motion of the spool depends upon the angle θ. When the line of
action of the force passes through the contact point the spool will
slide and not rotate. At lower angles it will roll to the right and at
higher angles it will roll to the left.