Why does a spinning egg stand up?

If a hard-boiled egg is spun fast enough on a table, it will slowly stand upright as it continues to spin. Although the spinning egg rises due to the force of friction between the egg and the table, the full explanation involves ...

Filming how our immune system kill bacteria

To kill bacteria in the blood, our immune system relies on nanomachines that can open deadly holes in their targets. UCL scientists have now filmed these nanomachines in action, discovering a key bottleneck in the process ...

Mars new home 'a large sandbox'

With InSight safely on the surface of Mars, the mission team at NASA's Jet Propulsion Laboratory in Pasadena, California, is busy learning more about the spacecraft's landing site. They knew when InSight landed on Nov. 26 ...

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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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