Question

A particle is moving along X-axis with uniform acceleration -2 m/s2. Its initial velocity is 20 m/s. Calculate average speed after 15 seconds.​

Answer 1

Answer:

Here,

$u = 20 ms^{-1} \\a = -2 ms^{-2}\\t = 15s$

using the above information,

let's think which equation will fit the best,

so,

we found that,

$a = \frac{2(v-u)}{t}\\at = 2(v-u)\\\frac{at}{2} - u = v\\v = \frac{at}{2} - u$

so, using this formula

we get,

$v = \frac{-2 ms^{-2}15s}{2} - 20 ms^{-1}$

$v = 5ms^{-1}$