Submitted by admin on Thu, 04/24/2014 - 22:56
definition:
The force that attracts a body towards the centre of the earth, or towards any other physical body having mass
sentence:
Objects exert a force of gravity because they have mass and the more mass they have the stronger the force of gravity they exert.
Physics has found only four forces in nature: gravity, electromagnetism, weak nuclear, and strong nuclear.
difficulty:
medium
toefl frequency:
2