Five things to know about Greenland

US President Donald Trump has confirmed he is keen to buy Greenland, an autonomous Danish territory rich in natural resources and of increasing geopolitical relevance as the Arctic ice sheet melts.

The journey of pollen and the process of pollen dispersal

For allergy sufferers, the pollination period is a tough time, whereas for plants it is the opportunity to reproduce: in addition to the wind, insects, in particular, carry pollen from one flower to another to pollinate them. ...

Ring-shaped multi-carbon compound cyclocarbon synthesized

A team of researchers from Oxford University and IBM Research has for the first time successfully synthesized the ring-shaped multi-carbon compound cyclocarbon. In their paper published in the journal Science, the group describes ...

A brief astronomical history of Saturn's amazing rings

Many dream of what they would do had they a time machine. Some would travel 100 million years back in time, when dinosaurs roamed the Earth. Not many, though, would think of taking a telescope with them, and if, having done ...

India monsoon floods kill more than 200

The death toll from India's monsoon floods climbed to 202 on Tuesday as heavy rainfall kept pounding coastal regions in the west and south.

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Force

In physics, a force is any influence that causes an object to undergo a change in speed, a change in direction, or a change in shape. In other words, a force is that which can cause an object with mass to change its velocity (which includes to begin moving from a state of rest), i.e., to accelerate, or which can cause a flexible object to deform. Force can also be described by intuitive concepts such as a push or pull. A force has both magnitude and direction, making it a vector quantity. Newton's second law, F=ma, was originally formulated in slightly different, but equivalent terms: the original version states that the net force acting upon an object is equal to the rate at which its momentum changes.

Related concepts to force include: thrust, which increases the velocity of an object; drag, which decreases the velocity of an object; and torque which produces changes in rotational speed of an object. Forces which do not act uniformly on all parts of a body will also cause mechanical stresses, a technical term for influences which cause deformation of matter. While mechanical stress can remain embedded in a solid object, gradually deforming it, mechanical stress in a fluid determines changes in its pressure and volume.

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