8th grade Why things keep moving or stay still (balanced and unbalanced forces) worksheet

Why things keep moving or stay still (balanced and unbalanced forces)

Grade 8 Science Worksheet - Building Confidence

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

1. 1.

   Ari pushes a box of books across the floor. The forces point opposite ways, so subtract them. What is the net force?

2. Read this first

   Use this

   Force arrow diagram, one dimension, arrows drawn to scale by size.

3. 2.

   Bo pushes a moving box across the floor. The forces point opposite ways, so subtract them. What is the net force?
4. 3.

   Esme pushes a laundry basket across the floor. The forces point opposite ways, so subtract them. What is the net force?
5. 4.

   Jun slides a box across the classroom floor. Are the forces balanced, and what happens to the box?

   • Unbalanced; it speeds up
   • Balanced; it must stop
   • Unbalanced; it slows down
   • Balanced; it keeps the same speed

6. Use this

   Force arrow diagram, one dimension, arrows drawn to scale by size. Box A: pull 12 N pointing right; friction 12 N pointing left. Beside it: rolling right at a steady speed.

7. 5.

   Kira pulls a wagon along the sidewalk. Read the arrows. What happens to the wagon's motion?

   • It slows, since the pull is used up
   • It keeps rolling at the same speed
   • It speeds up to the right
   • It stops, since the forces are balanced
8. 6.

   Milo matches science words for a quiz. Which meaning goes with inertia?

   • How fast an object is moving
   • A force that pushes moving things forward
   • How much an object resists a change in motion
   • The force that slows a sliding object
9. 7.

   Noah swings an empty backpack and a full one. Which has more inertia?

   • The full one, since it has more mass
   • The empty one, since it is easier to swing
   • The one swung faster
   • Neither, since inertia is a push
10. 8.

    Pia reads that a bowling ball has a lot of inertia. What does that mean?

    • It rolls very fast
    • It is hard to start or stop
    • It feels no friction
    • A force inside it keeps pushing it
11. 9.

    Ren bikes at a steady 5 m/s. The forces on the bike balance. What happens next?

    • It stops soon, since forces balance
    • It speeds up a little
    • It slows down, since it needs more push
    • It keeps going 5 m/s

12. Use this

    Force arrow diagram, one dimension, arrows drawn to scale by size. Box A: push from the wind 3 N pointing right; water drag 3 N pointing left. Beside it: moving right at a steady 2 m/s.

13. 10.

    Tala's toy sailboat crosses a pond at a steady 2 m/s with balanced forces. What happens to its motion?

    • It stays the same, 2 m/s
    • It stops, since balanced means still
    • It speeds up to the right
    • It slows, since it is not pushed harder