A physics answer needs more than a number. You should know which forces act, which assumptions apply, and why the result has the right size and units. Use the examples below to make those checks part of your homework routine.
By the Apex Vision team · 6 minute read. We publish Apex Vision AI. Resource descriptions below come from official documentation; the worked problems are original examples with checked calculations, not product benchmark results.
Choose help for the part that has you stuck
| Your task | Useful resource | Access | Your next step |
|---|---|---|---|
| Understand a law or worked solution | OpenStax | Free online textbooks | Match the example’s assumptions to your problem |
| See how a model behaves | PhET | Free interactive simulations | Predict a change, then test it |
| Check equations, constants or units | Wolfram Alpha | Free queries; some features require Pro | Enter a complete, correctly specified calculation |
| Discuss a question on screen | Apex Vision AI | 30 free responses to start; free access refills every 12 hours | Ask for a diagram read-back and an explained method |
These resources do different jobs. A calculator can check algebra without checking your choice of physical model. A simulation can build intuition without reproducing every condition in an assignment.
Worked example: net force and motion
A 4.0 kg block starts from rest on a horizontal surface. A constant 18 N force acts to the right, and a constant 6.0 N friction force acts to the left. Find its acceleration, speed and displacement after 2.0 s. Treat the block as a particle, ignore air resistance, and take right as positive.
- Identify the forces. Weight acts down and the normal force acts up. There is no vertical acceleration, so those forces balance. The horizontal forces do not.
- Find the net horizontal force.
Fnet = 18 − 6.0 = 12 Nto the right. Do not use the applied force alone. - Apply Newton’s second law.
a = Fnet / m = 12 / 4.0 = 3.0 m/s²to the right. - Use constant-acceleration motion.
v = v₀ + at = 0 + 3.0 × 2.0 = 6.0 m/s. The displacement isΔx = v₀t + ½at² = 6.0 mto the right.
Two useful checks
Units: N/kg = m/s², so force divided by mass gives acceleration.
Energy: the net work is 12 N × 6.0 m = 72 J. The increase in kinetic energy is ½ × 4.0 kg × (6.0 m/s)² = 72 J. The two calculations agree.
The key idea is that net force determines acceleration. A moving object does not require a nonzero net force to keep a constant velocity. Review OpenStax’s explanation of Newton’s second law if this distinction is unclear.
Worked example: a parallel circuit
Connect ideal 6 Ω and 3 Ω resistors in parallel across an ideal 9 V supply. Ignore wire resistance.
Equivalent resistance: 1/R = 1/6 + 1/3 = 1/2, so R = 2 Ω.
Total current: I = V/R = 9/2 = 4.5 A.
Branch check: each branch has 9 V across it. The currents are 9/6 = 1.5 A and 9/3 = 3 A. Their sum is 4.5 A.
The equivalent resistance is smaller than either branch resistance, as expected for this parallel connection. Adding 6 Ω and 3 Ω would calculate the series arrangement instead. See OpenStax’s series and parallel resistor guide.
How to use the resources well
OpenStax: follow a complete explanation
The free College Physics 2e textbook provides explanations, worked examples and practice problems. Use it when you need to understand why a formula applies.
Read an example, cover the solution and try a similar problem. Check whether your course uses algebra-based or calculus-based methods.
PhET: test your intuition
PhET’s Forces and Motion: Basics lets you explore forces, friction and motion. Predict what doubling the net force will do before changing the simulation.
A useful learning check is whether you can explain the result in words and connect it to an equation.
Wolfram Alpha: check a specified calculation
Wolfram Alpha’s physics tools cover calculations, formulas and constants. Include units and identify what each value represents.
Compare its interpreted input with your intended question. A result based on the wrong equation or unit is still the wrong homework answer.
Apex Vision AI: explain an on-screen question
Include the full prompt and a readable diagram. Ask Apex Vision to read back the values, label the forces or circuit branches, and explain the next step.
Check that it has interpreted the image correctly. The Apex Vision user guide covers the extension workflow.
A reliable physics homework workflow
- Draw and define. Choose the object or system, sketch the situation and state a positive direction.
- List knowns and unknowns. Keep units beside every value. Separate velocity from acceleration and mass from weight.
- Choose the principle. Explain why Newton’s laws, energy, momentum or a circuit rule applies before rearranging an equation.
- Check and explain. Verify units and direction, estimate the size of the answer, and try another method when available.
“Read back this problem and its units. Help me draw the forces, state the assumptions and choose a principle. Give me one hint at a time, then show how to check my result.”
If you cannot explain why the model applies after working through an example, take your diagram and attempted solution to office hours or a tutor. That gives a person a specific misunderstanding to help with. Follow your course’s rules on outside assistance.
Frequently asked questions
Where can I get free physics homework help?
OpenStax provides free online textbooks and worked examples, while PhET provides free simulations. Wolfram Alpha offers free queries with some paid features, and Apex Vision offers free starter responses. Match the resource to the concept or calculation you need help with.
Can AI solve physics questions from a screenshot?
It can help, but it may misread a diagram, label or unit. Include the full question, ask it to read back the givens, and check the model before accepting a calculation. Small or cropped circuit and force diagrams need particular care.
Why does my answer differ from the solution?
Compare the assumptions, sign convention, units and equations before checking arithmetic. Common differences include using applied force instead of net force, confusing speed with velocity, or treating parallel resistors as a series circuit.
Does this approach work for college physics?
The workflow applies to introductory algebra-based and calculus-based physics. The method still needs to match your course: a calculus problem may require a derivation or integral that a numerical answer does not provide. Include those requirements when asking for help.
Sources and review notes
Reviewed October 13, 2026 using the official OpenStax, PhET and Wolfram Alpha references linked above. The examples use explicitly stated idealizations and independently checked arithmetic. This comparison does not assign unsupported accuracy scores to products.