Results 1 to 9 of 9
Like Tree2Thanks
  • 1 Post By skeeter
  • 1 Post By skeeter

Math Help - Mechanics question

  1. #1
    Junior Member
    Joined
    Jul 2008
    Posts
    33

    Mechanics question

    A man of mass 80kg is in a balloon basket of mass 40kg. The man is holding a bag of ballast of mass 60kg.
    the basket with its contents attached to a balloon are accelerating downwards at 2.8m/sec^2
    a) what is the force exerted by the man on the bag of ballast?
    b) what forces are exerted on the man by
    i) the bag of ballast?
    ii) the basket?

    Ans
    a) 60g- R = 60x2.8 ( where R is the force exerted by the man on the bag)
    R= 420N
    b)
    i) 60g= 588N ( force exerted by the bag on the man)
    ii) (420+ 80g) - B = 80x2.8 ( where B is the force of the basket on the man)

    question , is part I and ii correct not sure
    Follow Math Help Forum on Facebook and Google+

  2. #2
    MHF Contributor
    skeeter's Avatar
    Joined
    Jun 2008
    From
    North Texas
    Posts
    11,683
    Thanks
    446

    Re: Mechanics question

    Quote Originally Posted by nazz View Post
    A man of mass 80kg is in a balloon basket of mass 40kg. The man is holding a bag of ballast of mass 60kg.
    the basket with its contents attached to a balloon are accelerating downwards at 2.8m/sec^2
    a) what is the force exerted by the man on the bag of ballast?
    b) what forces are exerted on the man by
    i) the bag of ballast? equal and opposite to the force exerted by the man on the ballast (3rd law, right?)
    ii) the basket? basket pushes up on the man ... what other force acts on the man? ... net force on the man?

    Ans
    a) 60g- R = 60x2.8 ( where R is the force exerted by the man on the bag)
    R= 420N
    b)
    i) 60g= 588N ( force exerted by the bag on the man)
    ii) (420+ 80g) - B = 80x2.8 ( where B is the force of the basket on the man)

    question , is part I and ii correct not sure
    ...
    Follow Math Help Forum on Facebook and Google+

  3. #3
    Junior Member
    Joined
    Jul 2008
    Posts
    33

    Re: Mechanics question

    What about calculations for part i and ii ? Are they correct?
    Follow Math Help Forum on Facebook and Google+

  4. #4
    MHF Contributor
    skeeter's Avatar
    Joined
    Jun 2008
    From
    North Texas
    Posts
    11,683
    Thanks
    446

    Re: Mechanics question

    forces on the ballast ...

    60g - R = 60a

    R = 60(g-a) = 420 N


    forces on the man ...

    80g + R - B = 80a

    80(g - a) + R = B
    Thanks from puresoul
    Follow Math Help Forum on Facebook and Google+

  5. #5
    Junior Member
    Joined
    Jul 2008
    Posts
    33

    Re: Mechanics question

    Shouldn't R be negative as it is upwards so the equation should be 80g -R-B=80a
    Follow Math Help Forum on Facebook and Google+

  6. #6
    MHF Contributor
    skeeter's Avatar
    Joined
    Jun 2008
    From
    North Texas
    Posts
    11,683
    Thanks
    446

    Re: Mechanics question

    man's force on the bag is upward

    bag's force on the man is equal, but in the opposite direction by Newton's 3rd law ... downward
    Thanks from puresoul
    Follow Math Help Forum on Facebook and Google+

  7. #7
    Junior Member
    Joined
    Jul 2008
    Posts
    33

    Re: Mechanics question

    Makes sense so the force on the man are force of the bag on man, his weight and what about the weight of the bag on the man?
    Follow Math Help Forum on Facebook and Google+

  8. #8
    MHF Contributor
    skeeter's Avatar
    Joined
    Jun 2008
    From
    North Texas
    Posts
    11,683
    Thanks
    446

    Re: Mechanics question

    60g - R = 60a

    R acts on the man ... the weight of the bag contributes to the magnitude of R as shown in the equation
    Follow Math Help Forum on Facebook and Google+

  9. #9
    Junior Member
    Joined
    Jul 2008
    Posts
    33

    Re: Mechanics question

    Many thanks for the feedback
    Follow Math Help Forum on Facebook and Google+

Similar Math Help Forum Discussions

  1. RE new mechanics question
    Posted in the Math Topics Forum
    Replies: 2
    Last Post: November 9th 2012, 07:13 AM
  2. Mechanics Question
    Posted in the Advanced Math Topics Forum
    Replies: 8
    Last Post: April 15th 2012, 03:54 PM
  3. C.O.M Mechanics question.
    Posted in the Math Topics Forum
    Replies: 1
    Last Post: June 14th 2009, 02:48 PM
  4. Another mechanics question.
    Posted in the Math Topics Forum
    Replies: 2
    Last Post: June 13th 2009, 12:46 AM
  5. Mechanics question
    Posted in the Math Topics Forum
    Replies: 1
    Last Post: March 6th 2009, 11:27 AM

Search Tags


/mathhelpforum @mathhelpforum