A horizontal force of 45 N is applied to a block, causing it t... | General Science MCQ | Examoogle

General SciencePhysics: Work, Energy and Power

A horizontal force of 45 N is applied to a block, causing it to displace 8 m in the direction of the force. The work done by the force is:

360 J

350 J

370 J

5.6 J

Correct Answer

🔬 SC • Science Concept & PrincipleGeneral SciencePhysics: Work, Energy and Power

Option A

360 J

Quick Summary:

Work is defined as the product of force applied to an object and the displacement produced in the direction of the force. By multiplying the given force of $45 \text{ N}$ and the displacement of $8 \text{ m}$ , we obtain the total work done as $360 \text{ J}$ .

🔬SCScience SolutionConcept & Principle

💡 Explanation

💡 Everyday Analogy (Real-World Intuition)

Think of pushing a heavy box across a floor; the more force you apply and the further you push it, the more 'energy' you transfer, which is exactly what we measure as work.

🧠 Memory Mnemonic / Shortcut Aid

FAD: Force times displacement equals work (F $\times d = W).$

🔢 Key Formulas

$W = F \cdot d$ — Work done equals force dotted with displacement

$W = Fd \cos \theta$ — Work done where $\theta$ is the angle between force and displacement vectors

⚙️ Working Principle

The principle of work is based on the scalar product of the force vector and the displacement vector, expressed as $W = \vec{F} \cdot \vec{d} = Fd \cos \theta$ . When the force and displacement are in the same direction, the angle $\theta = 0°$ , and since $\cos(0°) = 1$ , the work is simply $W = F \times d$ .

📌 Key Points

▸
Work is a scalar quantity, meaning it has magnitude but no direction.
▸
The SI unit of work is the Joule ( $J$ ), where $1 \text{ J} = 1 \text{ N} \cdot \text{m}$ .
▸
If the force is perpendicular to the displacement, the work done is zero because $\cos(90°) = 0$ .

✅ Advantages

▸
Provides a quantitative measure of energy transfer in mechanical systems.

❌ Disadvantages / Limitations

▸
Does not provide information about the time taken to perform the work, which would require the concept of power.

🛠️ Applications / Uses

▸
Calculating energy expenditure in industrial machinery.
▸
Determining the potential energy gained by lifting objects.

📄 Additional Information

▸
The scalar nature of work means it can be positive, negative, or zero.
▸
Option B (350 J), C (370 J), and D (5.6 J) are numerically incorrect based on the product calculation $45 \times 8 = 360$ .

📊 Diagram / Illustration

✅

A is correct — The product of $45 \text{ N}$ force and $8 \text{ m}$ displacement directly yields $360 \text{ J}$ of work.

Core Concepts Used

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Work-Energy Theorem Scalar Product Mechanical Energy Transfer

💡 EXAM TIP

Always check the units before calculating; if the force was in $\text{kN}$ or displacement in $\text{cm}$ , you would need to convert them to $\text{N}$ and $\text{m}$ respectively to get the result in Joules.

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