PencilGo

Grade 11 · Science · Physics

11th grade Newton's third law: force pairs worksheet

6 printable versionsBuilding Confidence10 questions · answer keyFree · no account

Level: Building Confidence · On Level · Challenge Me

When it’s done, scan the sheet with your phone and PencilGo marks it and picks the next one. Create a free account

Version
Print

Newton's third law: force pairs

Grade 11 Science Worksheet - Building Confidence

NameDate

Circle the best answer, or write your answer on the line.

  1. Ari pushes block A (2 kg) with 15 N. It pushes block B (3 kg) ahead of it on a smooth table. How hard does A push B?

  2. Esme pushes block A (4 kg) with 18 N. It pushes block B (5 kg) ahead of it on a smooth table. How hard does A push B?

  4. Using the two diagrams, which cart has the larger acceleration, and by how much, Jun?

    • Both carts: 3 m/s², since the two forces are equal
    • Cart B, since the same force acts on a heavier cart
    • Cart A: 6 m/s², since 6 N acts on it alone
    • Cart A: 3 m/s², twice cart B's 1.5 m/s²

  5. Do the two 6 N forces cancel, so that the carts stay put, Kira?

    Use the picture in question 3.

    • Yes, but just while the spring is still pushing on them
    • No: each force acts on a different cart, so both accelerate
    • Yes: equal and opposite forces cancel, so neither cart moves
    • No: the heavier cart pushes harder, so the carts both move

  6. Two free-body diagrams side by side (example data). The skaters push off each other on smooth ice. After one second of pushing, which skater has the greater speed, Luz?

    • Skater B, since the 100 kg skater is pushed with more force
    • Both gain 1.2 m/s, since the two forces are equal in size
    • Skater A, the 50 kg skater, who gains 1.2 m/s against 0.6 m/s
    • Neither: the two 60 N forces cancel, so both skaters stay put

  7. A car's tires push backward on the road. What is the partner of that force, Milo?

    • The road pushing forward on the tires
    • The car's weight pulling it down onto the road
    • Air resistance pushing back on the car
    • The engine pushing the wheels around

  8. A book rests on a table, and the table pushes up on it. What is the partner of that force, Noah?

    • Earth pulling the book down, which is its weight
    • The book pulling Earth up with the same size of force
    • Air pressure pushing down on the book from above
    • The book pushing down on the table

  9. A 1,500 kg car hits a 15,000 kg truck head-on. Which statement about the crash is true, Ren?

    • The car pushes harder, since it is the lighter vehicle
    • The forces are equal; the car's acceleration is ten times larger
    • The truck pushes harder, so the car's acceleration is the larger one
    • The forces are equal, so both vehicles accelerate equally

  10. A bug hits a moving car's windshield. How do the force on the bug and the force on the car compare, Tala?

    • The bug's force on the car is greater, since it hits at speed
    • The car's force on the bug is far greater, since it is bigger
    • They are equal, so the bug and car accelerate the same amount
    • They are equal, but the bug's acceleration is far greater

  11. A heavy puck hits a light puck on an air-hockey table. How do their forces on each other compare during contact, Zee?

    • Equal at the start, then the heavy puck pushes harder
    • Equal at each instant of the contact
    • The heavy puck pushes harder, since it has more mass
    • The light puck pushes harder, since it bounces back faster
PencilGopencilgo.com

11th grade Newton's third law: force pairs worksheet – printable
Print: 123456

About this worksheet

Newton's third law: force pairs. Every version has 10 questions, and the answer key prints on the second page.

What your child will learn

  • I can name a force's partner by swapping the objects (A on B gives B on A). I can tell a pair (two objects) from balanced forces (one object), such as a book's weight and the table's push.
  • I can explain why pair forces never cancel: they act on different objects, so each object accelerates from its own force.
  • I can use equal pair forces with different masses: a = F ÷ m for each cart, and m₁a₁ = m₂a₂.
  • I can explain propulsion: a drone pushes air down and the air pushes it up (thrust = m(g + a) when accelerating). Balloons and fan carts work the same way.

Standard: supports HS-PS2-1

Words to know

force pair: Two equal, opposite forces that two objects exert on each other

partner force: The other force in a pair: B on A for A on B

balanced forces: Forces on one object that add to zero

thrust: The push from air or gas that moves a drone or balloon

system: The objects you choose to study together

Common mistakes

Your child used the wrong share of the push. Block A is pushed by the hand and also pushes block B, so block B's force depends on B's mass over the total mass.

Your child split the push in half. The blocks share the push in proportion to their masses, not equally.

Your child said a force pair cancels. The two forces act on different objects, so each one changes its own object's motion.

Questions parents ask

What is the most common mistake with newton's third law: force pairs?

Your child used the wrong share of the push. Block A is pushed by the hand and also pushes block B, so block B's force depends on B's mass over the total mass.

Are these 11th grade science worksheets free to print?

Yes. All 6 printable versions at each level are free to print, with the answer key, and no account is needed.

More physics

See all Physics

Every sheet you scan goes into your child’s record: dated, marked and ready for the year-end portfolio. Homeschool records

Ready for easier practice?

Print a sheet, scan it when it’s done, and PencilGo picks the next one.

Create a free account