Gravity Physics Example 4

Follow the full solution, then compare it with the other examples linked below.

Example 4

medium
Calculate the gravitational force between two 50 kg50 \text{ kg} masses separated by 2 m2 \text{ m}. Use G=6.674×10−11 N m2/kg2G = 6.674 \times 10^{-11} \text{ N m}^2/\text{kg}^2.

Solution

  1. 1
    Write Newton's law of universal gravitation: F=Gm1m2r2F = \frac{Gm_1 m_2}{r^2}.
  2. 2
    Substitute the given values: F=6.674×10−11×50×5022=6.674×10−11×25004F = \frac{6.674 \times 10^{-11} \times 50 \times 50}{2^2} = \frac{6.674 \times 10^{-11} \times 2500}{4}
  3. 3
    Calculate: F=1.6685×10−74=4.17×10−8 NF = \frac{1.6685 \times 10^{-7}}{4} = 4.17 \times 10^{-8} \text{ N}

Answer

F≈4.17×10−8 NF \approx 4.17 \times 10^{-8} \text{ N}
The gravitational force between everyday objects is extremely small because GG is so tiny. This is why we only notice gravity when at least one object has an astronomical mass, like Earth.

About Gravity

The universal attractive force between any two objects with mass, decreasing with the square of distance.

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