Given:
Initial velocity, u = 0 km/h
Final velocity, v = 18 km/h
Time taken, t = 2 s

Formula:
Acceleration, a = (v-u)/t

Calculation:
Converting initial velocity from km/h to m/s:
u = 0 km/h = 0 m/s

Converting final velocity from km/h to m/s:
v = 18 km/h = (18 x 1000)/3600 m/s = 5 m/s

Substituting the given values in the formula:

a = (v-u)/t
a = (5 - 0)/2
a = 2.5 m/s²

Therefore, the acceleration of the car in SI unit is 2.5 m/s².

Explanation:
Acceleration is the rate of change of velocity with respect to time. It is a vector quantity and is measured in meters per second squared (m/s²) in the SI unit system. In the given problem, the car starts from rest and attains a velocity of 18 km/h in 2 seconds. We need to find the acceleration of the car in SI unit.

We first convert the given initial and final velocity from km/h to m/s, as acceleration is measured in m/s². Using the formula of acceleration, we substitute the given values and simplify to get the answer.

Thus, the acceleration of the car is 2.5 m/s².

Given...u =0v= 18 km/ h =5m/s.....t=2 .a=?so, a=v-u/t=>a=5-0/2=>a=2.5m/s^2...