To find the final velocity \( v \) when the initial velocity \( u \) is 20 m/s, the acceleration \( a \) is 4 m/s² and the time \( t \) is 7 seconds, we use the equation of motion:
\[ v = u + at \]
Where:
- \( v \) is the final velocity
- \( u \) is the initial velocity
- \( a \) is the acceleration
- \( t \) is the time
Plugging in the given values:
\[ v = 20 + (4 \times 7) \]
Now, we multiply the acceleration (4 m/s²) by the time (7 s):
\[ 4 \times 7 = 28 \]
Adding this to the initial velocity (20 m/s):
\[ v = 20 + 28 \]
\[ v = 48 \]
Therefore, the final velocity \( v \) when \( u = 20 \) m/s, \( a = 4 \) m/s², and \( t = 7 \) seconds is 48 m/s.
