**AP Physics 1 Question 374: Answer and Explanation**

### Test Information

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**Question: 374**

**2.** An object's initial velocity is in the second quadrant, with components **v**_{1x} = -1, **v**_{1y} = 4. Its final velocity is in the fourth quadrant, with components **v**_{2x} = 4, **v**_{2y} = -2. What is the direction of its average acceleration relative to the +*x*-axis?

- A. 50.2°
- B. 39.8°
- C. -39.8°
- D. -50.2°

**Correct Answer:** D

**Explanation:**

**D**

The average acceleration is found using . Since time is a scalar that only changes the magnitude of the vector, the direction of acceleration will be defined by the change in velocity. We'll deal with each component separately.

Δ**v**_{x} = **v**_{2x} - **v**_{1x} = 4 - (-1) = 5

Δ**v**_{y} = **v**_{2y} - **v**_{1y} = -2 - (4) = -6

It may help to draw the vector Δ**v.** The angle this vector forms with the +*x*-axis can be evaluated using the equation