To determine the final velocity of an object moving in a straight line with an initial velocity and uniform acceleration, we can use the kinematic equation that relates initial velocity, acceleration, time, and final velocity. The equation is: \[ v = u + at \] Where: - \( v \) = final velocity (what we want to find) - \( u \) = initial velocity - \( a \) = acceleration - \( t \) = time ### Step-by-Step Explanation 1. **Identify the Given Values**: - Initial velocity (\( u \)) = 10 m/s - Acceleration (\( a \)) = 2 m/s² - Time (\( t \)) = 5 seconds 2. **Substitute the Values into the Equation**: We will substitute the known values into the kinematic equation: \[ v = 10 \, \text{m/s} + (2 \, \text{m/s}^2 \times 5 \, \text{s}) \] 3. **Calculate the Acceleration Component**: First, calculate the product of acceleration and time: \[ 2 \, \text{m/s}^2 \times 5 \, \text{s} = 10 \, \text{m/s} \] 4. **Add the Initial Velocity**: Now, add this result to the initial velocity: \[ v = 10 \, \text{m/s} + 10 \, \text{m/s} = 20 \, \text{m/s} \] 5. **Final Result**: Therefore, the final velocity after 5 seconds is: \[ v = 20 \, \text{m/s} \] ### Conclusion The correct answer is **B. 20 m/s**. ### Explanation of Other Options - **Option A (10 m/s)**: This option suggests that the object does not change its velocity, which is incorrect because the object is experiencing a uniform acceleration of 2 m/s². - **Option C (30 m/s)**: This option incorrectly adds an additional 10 m/s to the final velocity calculation. It seems to misinterpret the acceleration effect over time. - **Option D (40 m/s)**: This option suggests an even larger increase in velocity, which would imply an acceleration of 6 m/s² over 5 seconds, which is not the case here. ### Common Pitfalls - **Ignoring the effect of acceleration**: Some students may forget to account for the acceleration when calculating the final velocity. - **Misapplying the formula**: Ensure that the correct kinematic equation is used and that all units are consistent (e.g., m/s for velocity and m/s² for acceleration). - **Confusing time and distance**: Remember that time is a separate variable from distance; the question specifically asks for velocity, not distance traveled. ### Revision Summary - Use the kinematic equation \( v = u + at \) to find final velocity. - Substitute known values carefully and perform calculations step-by-step. - Understand the role of acceleration in changing the velocity of an object. - Double-check calculations to avoid common mistakes.