Question

Suzie (of mass 42 kg) is roller-blading down the sidewalk going 32 miles per hour. She notices a group of workers down the walkway who have unexpectedly blocked her path, and she makes a quick stop in 2.2 seconds.a) What is Suzie’s average acceleration? Answer in units of m/s 2 .b) What force in Newtons was exerted to stop Suzie? Answer in units of N.

Answer 1

Answer:

a) Suzie’s average acceleration = -6.46 m/s²

b) Force exerted to stop Suzie = 271.52 N

Explanation:

a) We have equation of motion, v = u + at

     Final velocity, v = 0 m/s

     Initial velocity, u = 32 mph = 14.22 m/s

     Time, t =2.2 s

Substituting

     0 = 14.22 + a x 2.2

     a = -6.46 m/s²

Suzie’s average acceleration = -6.46 m/s²

b) Mass of Suzie = 42 kg

   Force = Mass x Acceleration

   F = Ma

   F = 42 x -6.46 =-271.52 N

   Force exerted to stop Suzie = 271.52 N