Question 315 of 949
A car accelerates uniformly from rest and reaches a speed of 30 m/s in 10 seconds. What is the distance traveled by the car during this time?
- 150 meters
- 300 meters
- 200 meters
- 100 meters
Correct Answer:
B
Explanation
To determine the distance traveled by a car that accelerates uniformly from rest to a speed of 30 m/s in 10 seconds, we can use the equations of motion. Let's break down the problem step-by-step.
### Step 1: Identify the Given Information
- Initial velocity (\(u\)): 0 m/s (the car starts from rest)
- Final velocity (\(v\)): 30 m/s
- Time (\(t\)): 10 seconds
### Step 2: Calculate the Acceleration
To find the distance traveled, we first need to calculate the acceleration of the car. We can use the formula for acceleration (\(a\)):
\[
a = \frac{v - u}{t}
\]
Substituting the known values:
\[
a = \frac{30 \, \text{m/s} - 0 \, \text{m/s}}{10 \, \text{s}} = \frac{30 \, \text{m/s}}{10 \, \text{s}} = 3 \, \text{m/s}^2
\]
### Step 3: Calculate the Distance Traveled
Now that we have the acceleration, we can use the formula for distance (\(s\)) traveled under uniform acceleration:
\[
s = ut + \frac{1}{2} a t^2
\]
Since the initial velocity \(u\) is 0, the formula simplifies to:
\[
s = 0 \cdot t + \frac{1}{2} a t^2 = \frac{1}{2} a t^2
\]
Substituting the values of \(a\) and \(t\):
\[
s = \frac{1}{2} \cdot 3 \, \text{m/s}^2 \cdot (10 \, \text{s})^2
\]
Calculating further:
\[
s = \frac{1}{2} \cdot 3 \cdot 100 = \frac{300}{2} = 150 \, \text{meters}
\]
### Conclusion
The distance traveled by the car during the 10 seconds of acceleration is **150 meters**. Therefore, the correct option is **A. 150 meters**.
### Explanation of Other Options
- **B. 300 meters**: This option is incorrect because it assumes a different calculation, possibly misapplying the formula or misunderstanding the relationship between speed, time, and distance.
- **C. 200 meters**: This option is also incorrect. It may arise from a miscalculation or incorrect assumptions about the acceleration or time.
- **D. 100 meters**: This option is incorrect as well. It could be a result of halving the correct distance or misunderstanding the acceleration's effect over time.
### Common Pitfalls
- **Forgetting to convert units**: Always ensure that all units are consistent (e.g., seconds for time, meters for distance).
- **Misapplying the equations of motion**: Ensure you are using the correct formula based on the initial conditions (like starting from rest).
- **Confusing distance with displacement**: In this case, since the car is moving in a straight line and starting from rest, distance and displacement are the same.
### Revision Summary
- Use the formula \(s = ut + \frac{1}{2} a t^2\) for distance under uniform acceleration.
- Calculate acceleration using \(a = \frac{v - u}{t}\).
- Ensure all units are consistent and correctly applied.
- Double-check calculations to avoid common mistakes.