8th grade physical science practice test: free questions with answers

Each daily paper has 8 original questions worth 25 to 35 marks. The Grade 8 Physical Science paper covers forces and motion, speed graphs, energy, power, waves, magnets and density. The Grade 8 Physical Science: Chemistry paper covers atoms, the periodic table, bonding, states of matter, mixtures and acids. Some questions, such as radioactivity, electric circuits, crude oil and reaction rates, go further than most 8th grade courses, so treat those as extra.

This page covers both strands of 8th grade physical science: physics (forces, motion, energy and waves) and chemistry (matter, atoms and chemical reactions). If your school teaches integrated science instead, the physical science content is the same, and the life science practice test covers the rest.

What's on an 8th grade physical science test

Courses differ by state. If your state uses the Next Generation Science Standards (NGSS), middle school physical science is built around four ideas:

• Matter and its interactions: atoms and molecules, properties of substances, states of matter, and chemical reactions in which atoms rearrange and mass is conserved.
• Forces and interactions: how the change in an object's motion depends on the forces on it and its mass, Newton's third law in collisions, and electric, magnetic and gravitational forces.
• Energy: kinetic and potential energy, and how energy transfers.
• Waves: amplitude, wavelength and frequency, and how light and sound behave.

Free 8th grade physical science practice test: 6 questions

We wrote these questions for this page. Give yourself 20 minutes with a calculator, then check the answers below.

1. A cyclist rides 18 km in 45 minutes. What is her average speed in km/h?
2. A 50 kg cart is pushed right with a force of 120 N while friction pulls left with 20 N. What is the net force, and what is the cart's acceleration?
3. A skater pushes off a wall and rolls backward. Explain, using Newton's third law, why she moves.
4. A metal block has a mass of 240 g and a volume of 30 cm³. Find its density. Will it float in water, which has a density of 1 g/cm³?
5. 10 g of baking soda and 30 g of vinegar react in a sealed bag. What is the total mass afterward, and why would it be less in an open cup?
6. A sound wave travels at 340 m/s with a frequency of 680 Hz. What is its wavelength?

Practice test answers

1. 24 km/h. 45 minutes is 0.75 hours, and speed = distance ÷ time = 18 ÷ 0.75 = 24 km/h. Dividing by 45 instead of 0.75 is the usual slip: change the time into hours first.

2. 100 N right, and 2 m/s². One force points each way, so take the smaller from the larger: 120 − 20 = 100 N to the right. Then acceleration = net force ÷ mass = 100 ÷ 50 = 2 m/s². The Force Calculator checks these. Try one from our Laws of Motion course, then press Mark.

3. When she pushes on the wall, the wall pushes back on her with a force of the same size in the opposite direction. That force from the wall acts on her, so she accelerates away. The two forces act on different objects, which is why they don't cancel out.

4. 8 g/cm³, and it sinks. Density = mass ÷ volume = 240 ÷ 30 = 8 g/cm³. That is greater than water's 1 g/cm³, so the block sinks. Use the Density Calculator to try other materials.

5. 40 g. In a chemical reaction the atoms rearrange but none are created or destroyed, so in a sealed bag the mass stays at 10 + 30 = 40 g. The reaction makes carbon dioxide gas, so in an open cup the gas escapes and the scale shows less, even though mass is still conserved. Balance reactions in the Equation Balancer.

6. 0.5 m. Wave speed = frequency × wavelength, so wavelength = speed ÷ frequency = 340 ÷ 680 = 0.5 m. A higher pitch means a higher frequency and so a shorter wavelength. The Wave Speed Calculator rearranges the formula for you.

State science tests and official practice

Many states test science in 8th grade, and each one decides its own format, so ask your teacher which test you will take and use your state education department's practice materials. As one example, New York publishes its past Grade 8 Intermediate-Level Science Tests from 2023 and earlier, with scoring keys and rating guides.

Use the daily papers as short timed practice tests

1. Alternate the physics and chemistry papers, and work to the suggested time, 30 to 40 minutes.
2. Write the formula before you put in numbers, and give units with every answer.
3. Mark it with the mark scheme and note the topic behind each lost mark.
4. Revisit weak topics in the Laws of Motion, Light and Energy and Atomic Structure courses.

Common physical science mistakes

• Mixing up mass and weight: mass is in kilograms; weight is a force in newtons.
• Adding forces that point opposite ways: subtract them to find the net force.
• Thinking action and reaction forces cancel: they act on different objects.
• Forgetting units or converting them: minutes to hours, grams to kilograms.
• Saying mass is lost in a reaction: a gas escaping is still mass, just somewhere else.

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