Question

A plane is landing. It started at 400m/s and ended up at 50m/s after 30 seconds. What is it's acceleration?

{middle school}

Answer 1

Give u = start velocity

v = end velocity

v = u + at

50 = 400 + a*30

30a = -350

a = -116.67 m/
`s^(2)`

**Why the accecleration is negative number**

Because displacement, velocity, and acceleration are VECTOR QUANTITIES.

Vector Quantity must have direction.