#### Centre of mass

In finite objects, the total external force equals the total mass times the acceleration of a point called the centre of mass.

More details | Watch now#### Centripetal force – how do we measure it?

A short video showing a simple classroom method of checking the way in which this force is related to mass, speed and radius.

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Uniform circular motion: angular displacement and velocity are introduced and centripetal acceleration is determined.

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The total work done on an object equals the increase in its kinetic energy. For conservative forces, we can define potential energy.

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A presentation showing both the ideas about centripetal force and a simple classroom method of checking the way in which this force is related to mass, speed and radius.

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The inverse square law explains planetary motion - and apples falling. Newton's law, measuring G, calculating orbits.

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Helen Sharman, the UK's first astronaut, gives a vibrant account of her personal experience of life in space using models and film to illustrate the key scientific concepts involved in spaceflight. Among other things she discusses the way Newton's Th....

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A few (surprising?) thoughts on how the wheels on a longboard or skateboard actually move.

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p=mv. If external forces are zero, momentum is conserved. In collisions, energy may be conserved (elastic) or not (inelastic).

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Kinematics quantifies motion without explaining the causes of it. Here we study accelerations that are zero, positive or negative.

More details | Watch now#### Newton’s laws of motion

F=ma (laws 1&2). Forces come in pairs that add to zero (3). Newton's laws apply in inertial frames of reference. Some common approximations made in applying them.

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