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: 3 acceleration questions

  1. Mar 28, 2006 #1
    Hey all,

    Im in grade 10 and we were learning the basics of physics, we had 3 acceleration questions that we had to answer for homework and im not sure how to do them. any help?

    1) "while at a car rental facility, the agent gives you a choice between 2 cars for the same price. Car A accelerates from REST to 100km/h in 8.0s. Car B takes 6s in the same test. Since you like fastt cars, you want the car with the greater acceleration. Which car would you choose? car A or Car B? Prove it."

    2) "Find the accleration, in m/s/s, of an airplane as it comes to a stop after landing. The airplane comes to a full stop from an intial velocity of 200 km/h [East] in 45 seconds. How far did the airplane travel as it slowed down."

    3) "You meet up with your friend during your travels and decide to have a quick race on your bicycles. You start from the same direction and from the same place. You accelerate at 4 m/s/s for 10s up to your maximum speed. You then cycle at this speed for another 10s. Your friend accelerated at 5m/s/s for 20s. Who was ahead at the end of 20s and by how much."

    Thanks and Regards,

  2. jcsd
  3. Mar 28, 2006 #2


    User Avatar
    Science Advisor
    Gold Member

    Do you know the formula for acceleration? For a hint, look at the units you gave in #2, m/s/s which can also be written m/s2.
  4. Mar 28, 2006 #3
    yea, the formula is a = v1 - v2/ t or a= v/t
  5. Mar 29, 2006 #4


    User Avatar
    Staff Emeritus
    Science Advisor
    Gold Member

    That's all you need to know to answer the question, you have the initial and final velocities and you also have the time taken.

    Just a quick note on your notation as velocity is change in velocity with respect to time it should be written as;

    [tex]a = \frac{\Delta v}{\Delta t} = \frac{dv}{dt}[/tex]

Share this great discussion with others via Reddit, Google+, Twitter, or Facebook