To determine the final velocity of an object moving in a straight line with an initial velocity and constant acceleration, we can use the following kinematic equation: \[ v = u + at \] Where: - \( v \) = final velocity (m/s) - \( u \) = initial velocity (m/s) - \( a \) = acceleration (m/s²) - \( t \) = time (s) ### Step-by-Step Explanation 1. **Identify the Given Values**: - Initial velocity (\( u \)) = 10 m/s - Acceleration (\( a \)) = 2 m/s² - Time (\( t \)) = 5 s 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 **A. 20 m/s**. ### Explanation of Other Options - **B. 25 m/s**: This option is incorrect because it suggests an additional 5 m/s increase in velocity that does not correspond to the calculated acceleration over the given time. - **C. 30 m/s**: This option is also incorrect. It implies an even greater increase in velocity than what is calculated, which does not align with the values provided. - **D. 35 m/s**: This option is incorrect as well, as it suggests an unrealistic increase in velocity given the initial conditions and the acceleration. ### Common Pitfalls - **Misunderstanding the Equation**: Students may confuse the kinematic equations or forget to add the initial velocity to the product of acceleration and time. - **Incorrect Units**: Ensure that all units are consistent (e.g., m/s for velocity and m/s² for acceleration). - **Neglecting Initial Velocity**: Some may forget to include the initial velocity in their calculations, leading to an incorrect final velocity. ### Revision Summary - Use the kinematic equation \( v = u + at \) to find final velocity. - Substitute known values carefully and perform calculations step-by-step. - Always include the initial velocity in your calculations. - Check units for consistency to avoid errors.