Question

Where v is the final velocity (in m/s), u is the initial velocity (in m/s), a is the acceleration (in m/s²) and s is the distance (in meters).
Find v when u is 9 m/s, a is 7 m/s², and s is 28 meters.

Answer 1

Answer:

The final velocity v is 21.74 m/s.

Step-by-step explanation:

Given:

$\textrm{initial velocity} = u = 9\ m/s\\\textrm{acceleration} = a = 7\ m/s^{2}\\\textrm{distance} = s = 28\ m$

To find:

$\textrm{final velocity} = v = ?$

Solution:

As we know the third equation of motion is represented as

$v^{2} = u^{2} + 2\times a\times s$

Substituting the values u, a and s in the above equation we get

$v^{2} = 9^{2} + 2\times 7\times 28\\ =81 + 392\\=473$

$v =\±\sqrt{473} \\v =\sqrt{473} \ \textrm{as acceleration is positive v is also positive}\\v = 21.74\ m/s$