Physics foundations and dimensional checks
Relate force, motion, energy, density and simple circuits to the data and model supplied in a passage.
What you will tackle
- Interpret motion/force relationships and energy transfer
- Distinguish mass, weight, density, heat and temperature
- Use simple circuit relationships when specified
- Check dimensional consistency and graph interpretation
Distinguish related quantities
Speed is distance per time; velocity includes direction. Acceleration is change in velocity per time. For a constant-mass object, resultant force F = ma. Mass measures matter/inertia; weight is gravitational force. Density is mass per volume. Energy can be transferred without being created; temperature is not the total thermal energy of an object.
Read a graph according to its axes
A distance–time gradient represents speed; a velocity–time gradient represents acceleration. Electrical current is charge flow per time, and potential difference is energy transferred per charge. If a passage gives V = IR for a resistor under fixed conditions, use it without assuming resistance stays constant in every device or temperature.
Build your notes, then practise
Work on paper before opening an explanation. Guided tasks provide a starting point; independent tasks remove the scaffolding; application tasks ask you to justify a method or interpretation in context.
Guided practice
Guided 1
A 2 kg cart has resultant force 6 N. Find its acceleration. A sample has mass 120 g and volume 40 cm³; find density. A resistor has 12 V across 4 Ω; find current using V = IR.
Show a starting hint
Write the units as part of each division.
Compare with the explained answer
- a = F/m = 6/2 = 3 m/s².
- Density = 120/40 = 3 g/cm³.
- I = V/R = 12/4 = 3 A.
Answer / response criteria: 3 m/s²; 3 g/cm³; 3 A.
Independent practice
Independent 1
A velocity–time graph increases from 2 to 8 m/s in 3 s. Find average acceleration. Compare the thermal-energy interpretation of 1 kg and 10 kg of the same substance at the same temperature.
Compare with the explained answer
- Average acceleration = (8 − 2)/3 = 2 m/s².
- Equal temperature does not imply equal total thermal energy.
- The larger sample generally stores more internal energy under comparable substance/state conditions.
Answer / response criteria: 2 m/s²; the same temperature does not mean the samples have the same total thermal energy.
Application practice
Application 1
A cart's measured speed remains constant while two horizontal forces of 5 N act in opposite directions. Explain the result, then describe what changes if one force becomes 7 N while the other remains 5 N and mass is 1 kg.
Compare with the explained answer
- The equal opposite forces give zero resultant, consistent with constant velocity.
- The changed resultant has magnitude 2 N towards the stronger force.
- F = ma gives acceleration magnitude 2 m/s² in that direction, assuming the stated force model.
Answer / response criteria: Zero resultant initially; then 2 m/s² towards the stronger force.
What can you explain now?
A cart's measured speed remains constant while two horizontal forces of 5 N act in opposite directions. Explain the result, then describe what changes if one force becomes 7 N while the other remains 5 N and mass is 1 kg.
Compare with the explanation
Zero resultant initially; then 2 m/s² towards the stronger force.
Explain the reasoning before comparing. This review records your self-assessment rather than an official score or mastery decision.
After trying it yourself, choose your next review. This is your self-assessment.
Your review choice appears on Today. Sign in to sync it across devices.
Source and review status
Coverage follows the named requirements and examples in the 2026–2027 ACT test guide and subject descriptions. That guide explicitly does not list every possible topic. The broader coded College and Career Readiness Standards are also mapped to conceptual teaching and practice; this does not calibrate a learner to a score band. The separate scientific-background context list and reading-complexity rubric have their own stated limits.
Original teaching and explained self-check practice are available. Specialist review and difficulty calibration remain pending. Essays require self-check or teacher review and are not automatically marked or awarded official scores.
Official source specification / guide