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11th grade Balanced forces, equilibrium and inertia worksheet

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Balanced forces, equilibrium and inertia

Grade 11 Science Worksheet

NameDate

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

  1. A sign of mass 10 kg hangs from two cables, each 30° above the horizontal. To the nearest tenth of a newton, what is the tension in each cable, Ari?

  2. A sign of mass 6 kg hangs from two cables, each 37° above the horizontal. To the nearest tenth of a newton, what is the tension in each cable, Bo?

  3. A sign of mass 8 kg hangs from two cables, each 20° above the horizontal. To the nearest tenth of a newton, what is the tension in each cable, Esme?

  4. A 10 kg sign hangs from two cables at 30° above the horizontal, each pulling 98 N. The cables are tightened to 10° above it. What happens to each tension, Jun?

    • It rises to about 100 N, since the angle changed by just 20°
    • It stays 98 N, since the sign's weight has not changed
    • It falls to about 49 N, since nearly flat cables hold less weight
    • It rises to about 282 N, nearly three times the sign's weight

  5. A block stays at rest as a ramp is tilted from 20° to 40°. What happens to the normal force and to friction on it, Kira?

    • The normal force decreases while friction increases
    • The normal force increases while friction decreases
    • The normal force stays equal to the weight, while friction increases
    • Both increase, since the ramp is steeper than before

  6. Free-body diagram (example data): a block on a frictionless 30° ramp, held by a rope parallel to the ramp. Using the free-body diagram, which pair of values is right for the rope and the ramp, Luz?

    • Tension 24.5 N and normal force 49 N, the weight
    • Tension 24.5 N and normal force 42.4 N
    • Tension 49 N, the weight, and normal force 42.4 N
    • Tension 42.4 N and normal force 24.5 N

  7. A 70 kg skydiver falls at a steady 55 m/s. How big is the air's force on the diver, and which way, Milo?

    • 0 N, since the diver is not accelerating at the moment
    • 3,850 N upward, from 70 × 55, to match the speed
    • 686 N upward, equal to the weight
    • 686 N downward, in the same direction as the motion

  8. A 60 kg student stands on a scale in an elevator moving up at a steady 2 m/s. What does the scale read, Pia?

    • 0 N, since the elevator is not accelerating
    • 708 N, which adds 60 × 2 for the upward motion
    • 588 N, the same as at rest
    • 468 N, which takes 60 × 2 away from the weight

  9. A heavy ball hangs from a string, with a second string tied below it. Which string breaks first with a slow pull on the lower one, and with a sharp jerk, Tala?

    • The lower string breaks first for both kinds of pull
    • Slow pull: the lower string. Sharp jerk: the upper string
    • The upper string breaks first for both kinds of pull
    • Slow pull: the upper string. Sharp jerk: the lower string

  10. A car cruises at 25 m/s as 400 N of engine force balances draw a line. The driver lifts off the gas. What happens next, Zee?

    • It slows, since 400 N of drag is no longer balanced
    • It speeds up, since the drag now pushes the car along
    • It stops at once, since the engine force is gone
    • It keeps 25 m/s, since its inertia carries it forward unchanged
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11th grade Balanced forces, equilibrium and inertia worksheet – printable
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About this worksheet

Balanced forces, equilibrium and inertia. Every version has 10 questions, and the answer key prints on the second page.

What your child will learn

  • I can say that equilibrium means zero net force, at rest or at constant velocity. I can tell when an object is not in equilibrium, such as a ball at the top of its flight.
  • I can find the force that balances others along a line or at right angles.
  • I can balance a block on a ramp: friction = mg sin θ and normal force = mg cos θ.
  • I can explain inertia as a property of mass, not a force and not a matter of speed. I can predict what objects do when their support stops or vanishes: a block on a stopping cart, a coin on a flicked card, a satellite without gravity.

Standard: supports HS-PS2-1

Words to know

equilibrium: Zero net force: at rest or moving steadily in a straight line

inertia: How hard an object is to speed up, slow or turn; set by mass

balanced forces: Forces whose arrows add to zero

ramp angle θ: The tilt of a ramp above level

constant velocity: Same speed in the same direction

Common mistakes

Your child set the normal force equal to the weight. The surface pushes back just enough to balance every force along that line, so a push, a pull or a tilt changes it.

Your child subtracted a downward press from the weight. A press pushes down just as weight does, so both are balanced by the surface.

Your child used cosine where sine belongs. With the angle measured from the horizontal, the cable's upward part is T sin θ.

Questions parents ask

What is the most common mistake with balanced forces, equilibrium and inertia?

Your child set the normal force equal to the weight. The surface pushes back just enough to balance every force along that line, so a push, a pull or a tilt changes it.

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.

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