Forces & Motion worksheet with fill-in-the-blank sentences and a word bank.

Here is the completed worksheet with explanations for each answer:

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Forces & Motion

Directions: Write the force words that complete each sentence.

Word Bank:
push, pull, gravity, friction, force, inertia, machine, energy, balance, Newton

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1. The greater the _force_ the easier the object will move.
✔ Explanation: Force is a push or pull on an object. According to Newton’s Second Law (F = ma), the greater the force applied to an object, the greater its acceleration — meaning it moves more easily (assuming mass is constant).

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2. To do the job in less time and with less energy, use a _machine_.
✔ Explanation: Simple machines (like levers, pulleys, or wheels) help us do work more efficiently by reducing the amount of force needed or changing the direction of force — thus saving energy and time.

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3. That rock will roll down the hill due to the force of _gravity_.
✔ Explanation: Gravity is the force that pulls objects toward the center of the Earth. It causes objects like rocks to roll downhill.

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4. To make something _balance_ both ends need to have the same weight.
✔ Explanation: Balance refers to equilibrium — when forces or weights are equal on both sides, an object remains stable and doesn’t tip.

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5. It takes _energy_ to get a job done.
✔ Explanation: Energy is the capacity to do work. Any physical task requires energy — whether it’s lifting, pushing, or moving something.

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6. _Inertia_ is the idea that something in motion will remain in motion, and something at rest will remain at rest, unless affected by an outside source.
✔ Explanation: This is Newton’s First Law of Motion — often called the law of inertia. Inertia is an object’s resistance to changes in its state of motion.

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7. It would be more difficult to _push_ a wagon if it didn’t have wheels.
✔ Explanation: Without wheels, there’s more friction between the wagon and the ground. Pushing requires overcoming that friction — so it’s harder without wheels.

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8. If you have a few people _pulling_ on the rope, the box will be easier to move.
✔ Explanation: Pulling adds force in one direction. More people pulling means more total force applied, making it easier to move heavy objects (like in tug-of-war or moving furniture).

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9. _Newton_’s theories on motion are still believed correct today.
✔ Explanation: Sir Isaac Newton formulated the three laws of motion and the law of universal gravitation — foundational principles in classical physics that still hold true for everyday situations.

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10. We added wheels to our bureau to create less _friction_ when we move it.
✔ Explanation: Wheels reduce friction by replacing sliding friction (between floor and legs) with rolling friction, which is much weaker — making movement smoother and easier.

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✔ Final Answer Key:

1. force
2. machine
3. gravity
4. balance
5. energy
6. inertia
7. push
8. pulling
9. Newton
10. friction

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