# Physics Mechanics

- Created by: Emily
- Created on: 03-05-12 19:06

Mechanics Notes.

A scalar quantity only has magnitude.

A vector quantity has magnitude and direction.

Displacement is the distance moved in a stated direction.

Speed = distance divided by time

Velocity = displacement divided by time

Acceleration = change on velocity divided time

Velocity is the gradient of a distance-time graph.

Displacement is the area under a velocity-time graph.

Acceleration is the change in velocity-time graph.

Aristotle thought that heavier bodies fell faster than lighter ones. This idea was a consequence of air resistance on light objects with a large surface area such as feathers. However Galileo suggested that without air resistance, all objects would move at the same constant acceleration. The acceleration due to gravity on earth is 9 point 8 1.

Newton’s 2^{nd} Law is that force= mass times acceleration. A Newton is the unit of force. 1 Newton is the force that will give a mass of 1kilogram, an acceleration of 1.

An experiment to find the centre of mass of an object is to suspend the object freely from a pivot point and attach a plumb line to find the vertical and then trace it onto the object. Then choose a second pivot point and do the same. Where the two lines intersect is the centre of mass.

A moment= the magnitude of a force times the perpendicular distance from the pivot.

A couple is a pair of forces that are both equal and opposite. A torque…

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