To find the change in velocity, we can use the formula:
\[ \Delta v = v_f - v_i \]
where:
- \( v_f \) is the final velocity,
- \( v_i \) is the initial velocity.
In this case:
- The initial velocity (\( v_i \)) is \( +20 , \text{m/s} \)
- The final velocity (\( v_f \)) is \( -30 , \text{m/s} \)
Now, we can calculate the change in velocity:
\[ \Delta v = (-30 , \text{m/s}) - (+20 , \text{m/s}) \]
This simplifies to:
\[ \Delta v = -30 , \text{m/s} - 20 , \text{m/s} = -50 , \text{m/s} \]
So the change in velocity is:
\[ \Delta v = -50 , \text{m/s} \]
The correct response is:
−50 m/s