An object of mass 10 kg is moving in a straight line with a speed of 2 m/s. What is the kinetic energy of this object?

Introduction / Context:
Kinetic energy is the energy that a body possesses due to its motion. In mechanics, calculating kinetic energy is one of the most basic tasks and forms the foundation for more advanced topics such as work energy theorem and conservation of energy. This question gives the mass and speed of an object moving in a straight line and asks for the kinetic energy, which directly tests your understanding of the kinetic energy formula and correct substitution of values.

Given Data / Assumptions:
• Mass of the object m = 10 kg. • Speed of the object v = 2 m/s. • Motion is straight line translational motion. • No rotational motion is considered, so only translational kinetic energy is relevant.

Concept / Approach:
The translational kinetic energy of a body of mass m moving with speed v is given by the formula KE = (1 / 2) * m * v^2. This formula shows that kinetic energy depends linearly on the mass and on the square of the speed. As speed doubles, kinetic energy increases by a factor of four. To solve the problem, we simply substitute the given mass and speed into this formula and compute the numerical value.

Step-by-Step Solution:
Step 1: Recall the formula KE = (1 / 2) * m * v^2. Step 2: Substitute m = 10 kg and v = 2 m/s. Step 3: Compute v^2 = 2^2 = 4. Step 4: Calculate KE = (1 / 2) * 10 * 4. Step 5: Simplify KE = 5 * 4 = 20 J. Step 6: Thus the kinetic energy of the object is 20 joules.

Verification / Alternative check:
We can check the result by estimating. For a mass of 10 kg moving at a modest speed of 2 m/s, we expect a kinetic energy that is not extremely large. Because the formula has a factor of 1 / 2, we can think of 10 * 4 = 40 and then half of that is 20. The arithmetic is straightforward and there are no unit conversions, so the result of 20 J is reasonable and consistent.

Why Other Options Are Wrong:
Option b (25 J): This would require either a different mass or speed value and does not match the exact formula calculation. Option c (10 J): This is half of the correct answer and may result from forgetting to square the speed (using v instead of v^2). Option d (40 J): This is the value of m * v^2 without the factor of 1 / 2, which is a common mistake when applying the formula. Option e (5 J): This is one quarter of the correct answer and has no physical basis in the given data.

Common Pitfalls:
A very common error is to forget the square on the velocity and calculate KE as (1 / 2) * m * v, which leads to wrong values. Another mistake is to misplace the 1 / 2 factor and calculate m * v^2 instead. Learners may also become confused with units, but here mass is in kilograms and speed in metres per second, so energy naturally comes out in joules. To avoid mistakes, always write the formula carefully, check that the speed is squared, and perform multiplication in small steps.

Final Answer:
The kinetic energy of the object is 20 J.