Select the correct answer.

Two vehicles collide and stick together. After the collision, their combined [tex]$y$[/tex]-momentum is [tex]$2.40 \times 10^4$[/tex] kilogram meters/second, and their [tex]$x$[/tex]-momentum is [tex]$7.00 \times 10^4$[/tex] kilogram meters/second. What is the angle of the motion of the two vehicles, with respect to the [tex]$x$[/tex]-axis?

A. [tex]$16.8^{\circ}$[/tex]

B. [tex]$17.0^{\circ}$[/tex]

C. [tex]$18.9^{\circ}$[/tex]

D. [tex]$20.9^{\circ}$[/tex]

E. [tex]$21.8^{\circ}$[/tex]



Answer :

To determine the angle of the motion of the two vehicles with respect to the x-axis after they collided and stuck together, we can follow these steps:

1. Understand the given data:
- [tex]\(y\)[/tex]-momentum ([tex]\(p_y\)[/tex]) = [tex]\(2.40 \times 10^4 \)[/tex] kilogram meters/second
- [tex]\(x\)[/tex]-momentum ([tex]\(p_x\)[/tex]) = [tex]\(7.00 \times 10^4 \)[/tex] kilogram meters/second

2. Calculate the angle [tex]\(\theta\)[/tex] of the resultant momentum vector with respect to the x-axis:
- We use the tangent function, [tex]\(\tan(\theta) = \frac{p_y}{p_x}\)[/tex].
- So, [tex]\(\theta = \tan^{-1}\left(\frac{p_y}{p_x}\right)\)[/tex].

3. Input the given momenta:
- [tex]\(\frac{p_y}{p_x} = \frac{2.40 \times 10^4}{7.00 \times 10^4}\)[/tex].
- Simplify: [tex]\(\frac{p_y}{p_x} = \frac{2.40}{7.00} \approx 0.3428571\)[/tex].

4. Find the angle [tex]\(\theta\)[/tex] in radians:
- [tex]\(\theta = \tan^{-1}(0.3428571)\)[/tex].

5. Convert the angle from radians to degrees to make it more interpretable:
- The result from the calculations gives us approximately: [tex]\(\theta \approx 0.3303\)[/tex] radians.
- Convert to degrees: [tex]\(\theta \approx 0.3303 \times \frac{180}{\pi} \approx 18.9246\)[/tex] degrees.

6. Compare the calculated degree value to the given answers:
- From the options provided, the closest value to [tex]\(18.9246^{\circ}\)[/tex] is clearly [tex]\(18.9^{\circ}\)[/tex].

Therefore, the correct answer is [tex]\( \boxed{18.9^{\circ}} \)[/tex].