Question

A car accelerates uniformly from 36 km per hour to 72 km per hour in 4 seconds.

Answer 1

Step-by-step explanation:

List the known and unknown values.

u = initial velocity = 36 km/h × 1000 m/1 km × 1 h/3600 s = 10 m/s

v = 72 km/h × 1000 m/1 km × 1 h/3600 s = 20 m/s

t = 5 s

a = acceleration = ? m/s²

s = displacement = ? m

First, calculate the acceleration using the following kinematic equation.

v = u + at

Solve for a.

a = (v-u)/t

a = (20 m/s-10 m/s)/(4 s) = 2.5 m/s²

Now calculate the displacement using the following kinematic equation.

s = ut + ½at²

s = (10 m/s × 4 s) + (0.4 × 2 m/s² × (4 s)²)

s = 40 m/s + (16 m) = 56 m