1. Limited time only! Sign up for a free 30min personal tutor trial with Chegg Tutors
    Dismiss Notice
Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Homework Help: Physics virgin is this how I do it?

  1. Sep 17, 2003 #1
    A truck on a straight road starts from rest accelerating at 2.0 m/s2 until it reaches a speed of 20 m/s. Then the truck travels for 20 s at constant speed until the brakes are applied, stopping the truck in a uniform manner in an additional 5.0 s. (a) How long is the truck in motion? (b) What is the average velocity of the truck for the motion described?

    My answers: (a) From rest to speed of 20 m/s it takes 10 s. Add 20 s. Add 5.0 s.... equals 35 s.

    (b) I know average velocity is displacement divided by time. But, how do I calculate the displacement???
  2. jcsd
  3. Sep 17, 2003 #2
    Calculate the displacements from the 3 segments of the trip separately. I assume you've come across a formula to calculate the distance traveled during constant acceleration...
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook