A body starts from rest and moves with an acceleration of 2 m/s^2. Its velocity after 5 seconds is:

Option B: 10 m/s Explanation & Concepts: The velocity of an object starting from rest and moving with constant acceleration can be calculated using the first equation of motion. Given the initial velocity $u = 0$, acceleration $a = 2\, m/s^2$, and time $t = 5\, s$, the final velocity is $10\, m/s$. Working Principle: According to Newton's first equation of motion, $v = u + at$. When a body starts from rest, its initial velocity $u$ is taken as $0$. The final velocity $v$ increases linearly with time at a constant rate equal to the magnitude of acceleration. Key Formulas: $v = u + at$ — First equation of linear motion; $a = \frac{v - u}{t}$ — Definition of acceleration Key Points: Initial velocity $u = 0$ for any body starting from rest.; Acceleration $a$ is the rate of change of velocity with respect to time.; The unit of velocity is $m/s$ and acceleration is $m/s^2$. Advantages: Provides a simple, linear model for constant acceleration motion. Disadvantages: Applicable only when acceleration is constant throughout the motion duration. Applications: Calculating vehicle pick-up speed.; Projectiles in vacuum with uniform gravitational acceleration. Additional Info: The acceleration due to gravity on Earth is approximately $9.8\, m/s^2$.. Option A (5 m/s) is incorrect as it neglects the acceleration multiplier; Option C (2.5 m/s) is incorrect; Option D (20 m/s) would be correct for $10\, s$ of motion. Answer: B is correct — Using the formula $v = u + at$ with $u=0, a=2, t=5$, we get $v = 0 + (2 \times 5) = 10\, m/s$. Exam Tip: Always verify if the body starts from rest ($u=0$) or has an initial velocity; neglecting $u$ is the most common cause of error in competitive kinematics problems.

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A body starts from rest and moves with an acceleration of 2 m/s². Its velocity after 5 seconds is:

5 m/s

10 m/s

2.5 m/s

20 m/s

Correct Answer

🔬 SC • Science Concept & PrincipleGeneral SciencePhysics

Option B

10 m/s

Quick Summary:

The velocity of an object starting from rest and moving with constant acceleration can be calculated using the first equation of motion · Given the initial velocity $u = 0$ , acceleration $a = 2\, m/s^2$ , and time $t = 5\, s$ , the final velocity is $10\, m/s$ .

🔬SCScience SolutionConcept & Principle

💡 Explanation

💡 Everyday Analogy (Real-World Intuition)

Think of pressing the accelerator in a car; if you increase speed by $2\, m/s$ every second, after $5\, s$ you will be moving $10\, m/s$ faster than when you started.

🔢 Key Formulas

$v = u + at$ — First equation of linear motion

$a = \frac{v - u}{t}$ — Definition of acceleration

⚙️ Working Principle

According to Newton's first equation of motion, $v = u + at$ . When a body starts from rest, its initial velocity $u$ is taken as $0$ . The final velocity $v$ increases linearly with time at a constant rate equal to the magnitude of acceleration.

📌 Key Points

▸
Initial velocity $u = 0$ for any body starting from rest.
▸
Acceleration $a$ is the rate of change of velocity with respect to time.
▸
The unit of velocity is $m/s$ and acceleration is $m/s^2$ .

✅ Advantages

▸
Provides a simple, linear model for constant acceleration motion.

❌ Disadvantages / Limitations

▸
Applicable only when acceleration is constant throughout the motion duration.

🛠️ Applications / Uses

▸
Calculating vehicle pick-up speed.
▸
Projectiles in vacuum with uniform gravitational acceleration.

📄 Additional Information

▸
The acceleration due to gravity on Earth is approximately $9.8, m/s^2$.
▸
Option A (5 m/s) is incorrect as it neglects the acceleration multiplier; Option C (2.5 m/s) is incorrect; Option D (20 m/s) would be correct for $10\, s$ of motion.

📊 Diagram / Illustration

✅

B is correct — Using the formula $v = u + at$ with $u=0, a=2, t=5$ , we get $v = 0 + (2 \times 5) = 10\, m/s$ .

Core Concepts Used

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Equations of motion Linear acceleration Kinematics

💡 EXAM TIP

Always verify if the body starts from rest ( $u=0$ ) or has an initial velocity; neglecting $u$ is the most common cause of error in competitive kinematics problems.

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