Force and Motion Test- Practice Questions and Answers
Force and Motion Test: Practice Questions with Answers
If you've got a force and motion test coming up, you're in the right place. This isn't a textbook summary or another "just study harder" pep talk. It's a collection of real practice questions covering the concepts that show up on most middle and high school physics tests. Work through them, check your answers, and figure out where you need to focus.
Core Concepts You Need to Know First
Before diving into questions, make sure these fundamentals are solid. If you're shaky on these, the questions won't make sense no matter how many you answer.
- Force — a push or pull measured in Newtons (N). Net force is the total force acting on an object after you add up all the individual forces.
- Motion — any change in an object's position over time. Speed, velocity, and acceleration all describe different aspects of motion.
- Newton's Three Laws — the backbone of every force and motion test. Every question traces back to one of these.
- Friction — force that resists motion when surfaces rub together. Static friction keeps things still; kinetic friction slows things down.
- Gravity — force that pulls objects toward Earth (or any massive body). On Earth's surface, gravity accelerates objects at 9.8 m/s².
Newton's Laws Comparison
Most questions test your ability to apply the right law. Here's a quick breakdown:
| Law | What It Says | Real-World Example |
|---|---|---|
| First Law (Inertia) | Objects at rest stay at rest; objects in motion stay in motion unless acted on by an outside force. | A hockey puck sliding on ice keeps going until friction or a stick hits it. |
| Second Law (F=ma) | Force equals mass times acceleration. More mass = more force needed to move it. | Pushing a shopping cart is easy; pushing a car is nearly impossible. |
| Third Law (Action-Reaction) | Every action has an equal and opposite reaction. | Walking: your foot pushes backward on the ground, and the ground pushes you forward. |
Practice Questions and Answers
Question 1: Identifying Net Force
A book sits on a table. Two forces act on it: gravity pulls down with 10 N, and the table pushes up with 10 N. What is the net force on the book?
A) 20 N downward
B) 20 N upward
C) 0 N
D) 10 N
Answer: C) 0 N
The forces are equal and opposite, so they cancel out. The book stays stationary because the net force is zero. This is equilibrium.
Question 2: Applying Newton's Second Law
A 5 kg object accelerates at 3 m/s². What force is acting on it?
A) 8 N
B) 1.67 N
C) 15 N
D) 2 N
Answer: C) 15 N
Use F = ma. Multiply mass (5 kg) by acceleration (3 m/s²). 5 × 3 = 15 N. This is the most common formula you'll use on any force and motion test.
Question 3: Newton's First Law in Action
A car suddenly stops, but a passenger keeps moving forward. Why?
A) Gravity pulls the passenger forward
B) The passenger's body wants to keep moving at the same speed
C) The car is pushing the passenger
D) Friction between the seat and passenger
Answer: B) The passenger's body wants to keep moving at the same speed
This is inertia. The passenger's body was moving with the car and resists the change in motion. That's why seatbelts exist. Without an outside force (the seatbelt), the passenger keeps moving forward.
Question 4: Calculating Speed vs. Velocity
A runner completes a circular track with a circumference of 400 m in 50 seconds. What was their average speed?
A) 8 m/s
B) 50 m/s
C) 400 m/s
D) 0.125 m/s
Answer: A) 8 m/s
Speed = distance ÷ time. 400 m ÷ 50 s = 8 m/s. Speed is scalar (just magnitude). Velocity would include direction, and since the runner ends up where they started, their velocity would be 0 m/s.
Question 5: Friction and Motion
A wooden block slides across a table and eventually stops. What force caused it to stop?
A) Gravity
B) Normal force
C) Kinetic friction
D) Magnetism
Answer: C) Kinetic friction
Friction between the block and table converts kinetic energy into heat, slowing the block down until it stops. Without friction, it would keep moving forever.
Question 6: Acceleration Calculation
A car speeds up from 10 m/s to 30 m/s in 5 seconds. What is its acceleration?
A) 2 m/s²
B) 4 m/s²
C) 6 m/s²
D) 150 m/s²
Answer: B) 4 m/s²
Acceleration = (final velocity - initial velocity) ÷ time. (30 - 10) ÷ 5 = 20 ÷ 5 = 4 m/s². The car gains 4 m/s of velocity every second.
Question 7: Action-Reaction Pairs
A swimmer pushes backward on the water. What happens?
A) The water pushes the swimmer forward with equal force
B) The water pushes the swimmer backward with equal force
C) Nothing happens because the forces cancel
D) The swimmer sinks
Answer: A) The water pushes the swimmer forward with equal force
Newton's Third Law. The swimmer exerts force backward on the water; the water exerts an equal and opposite force forward on the swimmer. This is how swimmers, fish, and rockets move.
Question 8: Mass vs. Weight
An object has a mass of 50 kg on Earth. What is its weight?
A) 50 N
B) 490 N
C) 5.1 N
D) 500 N
Answer: B) 490 N
Weight = mass × gravity. 50 kg × 9.8 m/s² = 490 N. Mass stays the same everywhere; weight changes depending on the gravitational pull. On the moon, the same object would weigh about 81 N.
How to Use This for Test Prep
Don't just read through these questions. Here's how to actually use them:
- Close the answers first. Try every question without peeking. Mark the ones you got wrong or weren't sure about.
- Find the gap. If you missed questions on Newton's Third Law, go back to your notes and review that specific section.
- Write out the formulas. F = ma, speed = distance ÷ time, acceleration = (v₂ - v₁) ÷ t. Write them on a notecard and memorize them.
- Redo wrong questions the next day. Spaced repetition works better than cramming.
Common Mistakes to Avoid
These are the errors that cost students points on every test:
- Confusing mass and weight. Mass is how much stuff is in an object. Weight is the force of gravity on that stuff. They are not the same.
- Forgetting that friction always opposes motion. It never helps an object move faster.
- Using velocity when speed is asked (or vice versa). Read the question carefully. If it says "speed," it's scalar. If it says "velocity," it wants direction too.
- Skipping units. Always include Newtons, m/s, m/s², or kg. Missing units usually means lost points.
That's it. Go through the questions, nail the formulas, and don't overthink it. Force and motion tests are straightforward if you know the three laws and can plug numbers into the right equations. 📐