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

• 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=(v^2-u^2)/(2s)`

`\\ \rm\hookrightarrow a=(v^2)/(2s)`

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

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