Question

a truck is moving with a certain uniform velocity. it is accelerated uniformly by 0.75 m/s^2.after 20 seconds, the velocity becomes 72 km/h. find the initial velocity

Answer 1

5 m/s

Step-by-step explanation:

acceleration = 0.75 m/s²

time = 20 s

final velocity = 72 km/h = 20 m/s

initial velocity = ?

Apply formula for initial velocity.

`u=-at+v`

`\sf a=acceleration\\t=time\\v=final \: velocity\\u=initial \: velocity`

Solve for u.

`u=-(0.75)(20)+ 20`

`u=-15+20`

`u= 5`

Answer 2

`\boxed{V_(i) = 5\ m/s}`

Step-by-step explanation:

Given:

Acceleration = a = 0.75 m/s²

Time = t = ?

Final Velocity =
`V_(f)` = 72 km/hr = 20 m/s

Required:

Initial Velocity =
`V_(i)` = ?

Formula:

a =
`(V_(f)-V_(i))/(t)`

Solution:

For
`V_(i)` the formula becomes:

`V_(i) = V_(f)-at`

`V_(i)` = 20 - (0.75)(20)

`V_(i)` = 20 - 15

`V_(i)` = 5 m/s

In Case: If you want it in km/hr:

`V_(i)` = 5 * 3.6

`V_(i)` = 18 km/hr