Mechanics - YEAR1

what are mechanics

mechanics deals with motion and the action of forces on objects

what is the normal reaction

the force which acts perpendicular to a surface when an object is in contact with the surface

what is friction

a force which opposes the motion between two rough surfaces

what is tension

the force acting on the object if the object is being pulled along by a string

what is thrust/compression

the force acting on the object if the object is being pushed along using a light rod

what is air resistance

a force that opposes motion

what is buoyancy

the upward force on a body that allows it to float or rise when submerged in a liquid

what is a vector quantity

a quantity which has both magnitude and direction

example of vector quantities

• displacement - distance in a particular direction

• velocity - rate of change of displacement

• acceleration - rate of change of velocity

• force/weight - described by magnitude, direction and point of application

what is a scalar quantity

a quantity which has magnitude only

examples of scalar quantities

• distance - measure of length

• speed - measure of how quickly a body moves

• time - measure of ongoing events taking place

• mass - measure of the quantity of matter contained in an object

On a displacement time graph, what does the gradient represent

the velocity

If the displacement time graph is a straight line…

… then the velocity is constant

On a velocity time graph, what does the gradient represent

the acceleration

If the velocity time graph is a straight line…

… then the acceleration is constant

what is the area between a velocity time graph and the horizontal axis represent

the distance travelled

the standard set of letters for the motion of an object

• s - displacement

• u - initial velocity

• v - final velocity

• a - acceleration

• t - time

newton’s first law

an object at rest will stay at rest and that an object moving with constant velocity will continue to move with constant velocity unless an unbalanced force acts on the object

what is a force diagram

a diagram showing all the forces acting on an object

newton’s second law

the force needed to accelerate a particle is equal to the product of the mass of the particle and the acceleration produced.

f = ma

what is gravity

the force between any object and the earth.

the force due to gravity acting on an object is called the weight of an object.

newton’s third law

for every action there is an equal and opposite reaction.