Balanced and Unbalanced Forces Worksheet featuring a tug-of-war illustration and multiple-choice questions about forces.

Here is the complete solution to the worksheet, with explanations for each answer.

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1. Name the following:

i) A force that tries to slow things down when two things rub together.
* Answer: Friction
* *Explanation:* Friction is the resistive force that acts between surfaces in contact when they move or try to move relative to each other. It opposes motion and converts kinetic energy into heat.

ii) A force from water that pushes things up.
* Answer: Upthrust (or Buoyancy)
* *Explanation:* When an object is submerged in a fluid (like water), the fluid exerts an upward force on it called upthrust or buoyant force. This is why objects feel lighter in water.

iii) A force that tries to slow things that are moving through air.
* Answer: Air resistance (or Drag)
* *Explanation:* Air resistance is a type of frictional force exerted by air on objects moving through it. It opposes the motion of the object and increases with speed.

iv) Not moving.
* Answer: Stationary
* *Explanation:* An object that is not moving is described as being stationary. In physics, this often implies the net force acting on it is zero (balanced forces).

v) When two forces working in opposite directions are not the same strength.
* Answer: Unbalanced forces
* *Explanation:* Forces are unbalanced when their magnitudes are different and they act in opposite directions. This results in a net force, causing the object to accelerate (change speed or direction).

vi) The amount of force on something from gravity. It is measured in Newtons.
* Answer: Weight
* *Explanation:* Weight is the gravitational force exerted on an object by a planet (like Earth). Its SI unit is the Newton (N). (Note: Mass is measured in kilograms; weight is mass times gravity).

vii) The unit of force (N).
* Answer: Newton
* *Explanation:* The Newton (symbol: N) is the SI unit of force. One Newton is defined as the force required to accelerate a one-kilogram mass at one meter per second squared (1 N = 1 kg·m/s²).

viii) The force of attraction between two objects. The Earth has a large force of gravity which pulls things towards it.
* Answer: Gravity (or Gravitational force)
* *Explanation:* Gravity is the fundamental force of attraction between any two masses. On Earth, we experience it as the force pulling us and objects towards the center of the planet.

ix) A push or a pull.
* Answer: Force
* *Explanation:* In physics, a force is simply defined as a push or a pull acting upon an object as a result of its interaction with another object.

x) A piece of equipment containing a spring that is used to measure forces.
* Answer: Spring balance (or Newton meter)
* *Explanation:* A spring balance measures force by using Hooke's Law – the extension of a spring is proportional to the force applied. It typically has a scale calibrated in Newtons.

xi) They can attract and repel each other. They also attract things made of iron.
* Answer: Magnets
* *Explanation:* Magnets have north and south poles. Like poles repel, opposite poles attract. They also exert a force on ferromagnetic materials like iron, nickel, and cobalt.

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2. Circle the best answer:

The image shows a tug-of-war where both teams are pulling with a force of 1000 Newtons in opposite directions.

Let's evaluate each option:

* A. The forces shown above are PUSHING / PULLING forces.
* *Analysis:* The people are clearly *pulling* the rope. While "pulling" is correct, "pushing" is not. This option is partially incorrect.
* B. The forces shown above are WORKING TOGETHER / OPPOSITE FORCES.
* *Analysis:* The forces are acting in *opposite* directions. They are not working together; they are opposing each other. So, "OPPOSITE FORCES" is correct.
* C. The forces are EQUAL / NOT EQUAL.
* *Analysis:* Both sides are applying exactly 1000 N. Therefore, the forces are *EQUAL*.
* D. The forces DO / DO NOT balance each other.
* *Analysis:* Since the forces are equal in magnitude and opposite in direction, they *DO* balance each other. The net force is zero.
* E. The resultant force is 1000 N TO THE RIGHT / 1000 N TO THE LEFT / ZERO.
* *Analysis:* Resultant force is the vector sum. 1000 N right + 1000 N left = 0 N. So, the resultant force is ZERO.
* F. There IS / IS NO motion.
* *Analysis:* Since the forces are balanced (net force = zero), there will be NO acceleration. If the rope was initially stationary, it will remain stationary. So, "IS NO motion" is correct (assuming it started at rest).

Best Answers to Circle:

You should circle the correct part of each statement:

* A. Circle PULLING (but note the full option includes "pushing", which is misleading).
* B. Circle OPPOSITE FORCES.
* C. Circle EQUAL.
* D. Circle DO.
* E. Circle ZERO.
* F. Circle IS NO.

> Important Note: The question says "Circle the best answer," implying you choose one letter (A-F). However, all options A-F contain statements with two choices, and multiple are factually correct based on the diagram. Given the context of a worksheet, it's likely intended for students to circle the correct *part* within each lettered option.
>
> If forced to pick *one single letter* as the "best" overall answer summarizing the situation, D ("The forces DO balance each other") is perhaps the most comprehensive single statement, as it directly leads to the conclusion of no motion (F) and zero resultant force (E). But strictly speaking, C, D, E, and F are all correct descriptions of the scenario.

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Final Answer Summary:

1. i) Friction
ii) Upthrust (Buoyancy)
iii) Air resistance (Drag)
iv) Stationary
v) Unbalanced forces
vi) Weight
vii) Newton
viii) Gravity (Gravitational force)
ix) Force
x) Spring balance (Newton meter)
xi) Magnets

2. Circle:
* A: PULLING
* B: OPPOSITE FORCES
* C: EQUAL
* D: DO
* E: ZERO
* F: IS NO