1. Not finding help here? Sign up for a free 30min 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!

Law of Gravity

  1. Sep 23, 2007 #1
    1. The problem statement, all variables and given/known data

    Calculate, using Newton's law of gravity, the size of the force of attraction between the Earth and a mass of 3.0 kg on the Earth. Data: Distance to the center of Earth from the surface = 6370 km. Mass of Earth = 5.98 1024 kg. Gravitational constant (G = 6.67 times 10-11 Nm2/kg2).


    2. Relevant equations

    F = G(m1 * m2)/ r^2

    3. The attempt at a solution

    I plugged the numbers into the equation and converted km to meters and kg to g ...

    6.67E-11 * (3000)(5.98E27) / (6370000)^2
    and I got 2.949E-7, but it is wrong I think
     
  2. jcsd
  3. Sep 23, 2007 #2
    The answer is quite a way off.

    1.Why did you convert Kg to g? The SI unit of mass is Kg. When you substitute 6.67e-11 for G, it means G = 6.67e-11 Nm2/Kg2. So make sure the units are uniform throughout.

    2.You can make a rough estimate of the answer. If you've come across the term acceleration due to Earth's gravity(g), you may know that it is roughly equal to 10ms-2. The weight of an object on the Earth, which is nothing but the gravitational force due to the Earth, is mg, where m is the mass of the object.
     
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook

Have something to add?



Similar Discussions: Law of Gravity
  1. Law of gravity (Replies: 5)

Loading...