8th Grade Science

posted by .

A runner whose initial speed is 29 km/hr increases her speed to 31 km/hr in order to win a race. If the runner takes 0.5 seconds to complete this increase in speed, what is her acceleration?

I think it's either 1440 km/hr/hr
or 0.4 km/hr/sec. Are you supposed to convert the seconds? Thank you in advance.

  • 8th Grade Science -

    This involves the acceleration formula.

  • 8th Grade Science -

    a = change in velocity/change in time
    change in velocity = 31000 m/hr/3600 s/hr - 29000m/hr/3600 s/hr = .56 m/s
    so
    .56 m/s / .5 s = 1.11 m/s^2

  • 8th Grade Science -

    a= (31km/hr - 29km/hr) / 5sec
    a= 0.4 km/hr/s

    That's how I got one of the answers....I am confused at what you are trying to show me.

  • 8th Grade Science -

    a= (Vf - Vi) / t

Respond to this Question

First Name
School Subject
Your Answer

Similar Questions

  1. physics

    An 18-year-old runner can complete a 10.0 km course with an average speed of 4.51 m/s. A 50-year-old runner can cover the same distance with an average speed of 4.31 m/s. How much later (in seconds) should the younger runner start …
  2. physics

    Sprinting near the end of a race, a runner with a mass of 70 kg accelerates from a speed of 6 m/s to a speed of 9 m/s in 2 s. (a) What is the runner's average acceleration during this time?
  3. physics

    An 18-year-old runner can complete a 10.0 km course with an average speed of 4.58 m/s. A 50-year-old runner can cover the same distance with an average speed of 4.36 m/s. How much later (in seconds) should the younger runner start …
  4. Physics

    An 18-year-old runner can complete a 10.0-km course with an average speed of 4.39 m/s. A 50-year-old runner can cover the same distance with an average speed of 4.27 m/s. How much later (in seconds) should the younger runner start …
  5. physics

    An 18-year-old runner can complete a 10.0-km course with an average speed of 4.53 m/s. A 50-year-old runner can cover the same distance with an average speed of 3.91 m/s. How much later (in seconds) should the younger runner start …
  6. physics

    2 runners accelerate from rest to their top speeds. The 1st runner pat has an acceleration of 5.9 m/s^2 and reaches her top speed in 4 sec. The second runner steven accelerates at 4.4m/s^2 and takes 6.5 sec to reach his top speed the …
  7. physical science

    I am having a little trouble with this problem. can someone please HELP! During a race, a runner runs at a speed of 6m/s. 2 seconds later, she is running at a speed of 10 m/s what is the runner's acceleration?
  8. Science - Please Check my Answer 2

    My problem: One runner in a relay race has a 1.50 s lead and is running at a constant speed of 3.25 m/s. The runner has 30.0 m to run before reaching the end of the track. A second runner moves in the same direction as the leader. …
  9. Physics

    An 18-year-old runner can complete a 10.0-km course with an average speed of 4.39 m/s. A 50-year-old runner can cover the same distance with an average speed of 4.27 m/s. How much later (in seconds) should the younger runner start …
  10. Physics

    During a rElay race along a straight ROAD the 1st runner on a three person team runs D1 with a constant velocity v1. The runner then hands off the baton to the sEcond runner who runs d2 with a constant vElocity v2. The batton is then …

More Similar Questions