Question

A drag racer accelerates uniformly over a course 400m long. Determine the car's acceleration if it reaches a top speed of 120 m/s. Assume that the car starts from rest.

Answer 1

Answer:

U = 0

v= 120 m/s

D= 400m

By 3rd equation of motion,

let a be the acceleration

v^2- u^2=2ad

120^2-0^2 = 2*a*400

14,400 = 800a

a =18 m/s

Answer 2

• Initial velocity=u=0m/s(As it starts from rest)
• Final velocity=v=120m/s
• Distance between course=s=400m
• Acceleration be a

Apply third equation of kinematics

$\\ \rm\hookrightarrow v^2-u^2=2as$

Isolate the equation for a

$\\ \rm\hookrightarrow a=\dfrac{v^2-u^2}{2s}$

$\\ \rm\hookrightarrow a=\dfrac{v^2}{2s}$

$\\ \rm\hookrightarrow a=120^2/800$

$\\ \rm\hookrightarrow a=18m/s^2$