How to control friction in topological insulators

Topological insulators are innovative materials that conduct electricity on the surface, but act as insulators on the inside. Physicists at the University of Basel and the Istanbul Technical University have begun investigating ...

Clock ticks as SpaceX builds craft for NASA

Two weeks ago, the head of NASA seemed sick of waiting for SpaceX and Boeing Co. to finish developing the capsules that are supposed to carry U.S. astronauts to and from the International Space Station.

Nanostructures help to reduce the adhesion of bacteria

Scientists have shown how bacteria adhere to rough surfaces at the microscopic level. Now a team of researchers has discovered that precise analysis of the topographical composition of nanostructured surfaces provides a direct ...

The secret to sneaky float serves

A research team led by the University of Tsukuba studied the aerodynamics of a volleyball using a wind tunnel and hitting robot. They found that no matter the orientation of a standard ball, the pattern of panels presents ...

Physicists report a way to 'hear' dark matter

Physicists at Stockholm University and the Max Planck Institute for Physics have turned to plasmas in a proposal that could revolutionise the search for the elusive dark matter.

Microscope prints patterns at the nanoscale

Researchers from AMOLF's 3-D-Photovoltaics group have used an atomic force microscope to electrochemically print at the nanoscale. This technique can print structures for a new generation of solar cells on chips. The researchers ...

Emirati becomes first Arab to reach ISS

An Emirati has made history as the first Arab to reach the International Space Station, after blasting off from Kazakhstan.

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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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