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3 basic Sports & Physics problems

  1. Sep 16, 2008 #1
    1. The problem statement, all variables and given/known data
    1. If you are driving 70 mi/hr and you look to the side for 2 seconds, how far did you travel during this inattentive period?

    2. A pilot determines that his plane can accelerate at a rate of 10,000 mi/hr². If the runway is .5 miles long and he must be traveling at 100 mi/hr in order to leave the ground, should he attempt to take-off?

    3. A baseball is hit straight up into the air with a speed of 25 m/s. How high does it go and how long is it in the air?


    2. Relevant equations

    x=Vot+1/2at²
    v=Vo+at
    V² =V² o+2ax

    acceleration due to gravity: g=9.8 m/s²

    Everything is in absence of air resistance and any other outside forces.

    x=distance covered
    v=initial velocity
    t=time
    a=acceleration
    v=speed or velocity

    units=m/s²
    The little "o"s next to the Vs are just initial velocity, if there is no inition velocity (starting at 0) then that part of the equation can be marked out.

    3. The attempt at a solution
    1. Here I am somewhat confused on which equation to choose, it can't be the second one because I am measure distance (x). I'll go with the first one.

    x=Vot+1/2at²

    X=(70 miles/hr)(2s)
    Because there is no acceleration I am guessing I mark that part of the equation out.
    Now I will attempt to convert for like units...

    I really have no idea what I'm doing


    2. I have notes for this, I'm just having trouble understanding them. The basic question is what is X when the plane reaches 100 mph.
    V² =Vo² +2ax
    100/2a=2ax/2a
    100/2a=x
    100/2(10,000 mi/hr² =.5mile


    3. I have notes for this one as well. I think in class we went over 2 ways of doing it, one easy, one hard. Is it that I can just move the decimal place over in the 25 m/s and multiply it by two?
    example: 25 m/s, so 2.5 x 2 (multiply by 2 for time up and time coming down)


    Thanks for helping on any of these.


    -Michael
     
  2. jcsd
  3. Sep 16, 2008 #2

    tony873004

    User Avatar
    Science Advisor
    Gold Member

    #1 is basically a unit conversion problem. You need to convert it into distance / second

    I'll make up different numbers and show you how to do it.

    Let's say you were given 50 km / minute. There are 60 seconds in a minute so this equals 50 km / 60 seconds. You can now divide 50/60 and get .833 km / s. Doing this speed, if you took your eyes off the road for 3 seconds, you will have travelled 0.833 km/s * 3 s = 2.5 km.

    You could also solve this by translating seconds into hours. Then your proglem would read that you took your eyes off the road for 2/3600 of an hour while travelling at 70 mi/hr.
     
  4. Aug 24, 2010 #3
    A sport is a physical activity that is governed by a set of rules or customs and often engaged in competitively, sports can be done on land, in water, in the air and in space.


    Basic rules of sport
     
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