G481 Definetions

Topics: Force, Potential energy, Classical mechanics Pages: 9 (1916 words) Published: February 9, 2014
Definitions:
define scalar and vector quantities and give examples;

Scalar: Magnitude without direction
Examples: Length, area, volume, distance, speed, mass, density, pressure, temperature, energy, work, power, electrical potential, charge, time Vector: A quantity that has (both) magnitude / size and direction Examples: Displacement, velocity, acceleration, momentum, force (lift, drag, thrust, weight), field(s), a.c. voltage, current (when calculating fields only) define displacement, instantaneous speed,

average speed, velocity and acceleration;

Displacement = (net) distance moved in a particular direction. Instantaneous speed = speed measured between two point a very small time apart Average speed = distance covered / time taken
Velocity = speed in a given direction
Acceleration is the gradient of a velocity vs time graph. (= change in velocity / time taken) define the newton;

The (net) force which gives a mass of 1kg an acceleration of 1 ms-2. define and apply the torque of a couple;

one of forces × perpendicular distance (between forces) (Not force x perpendicular distance) define and apply the moment of force;

moment = force x perpendicular distance from pivot / axis / point define thinking distance, braking distance and stopping distance;

Thinking distance: The distance travelled (by the car) from when the driver sees a problem and the brakes are applied Braking distance: The distance travelled (by the car) whilst the brakes are applied and the car stops (wtte) Stopping distance: Thinking distance + braking distance

define work done by a force;

work done = force x distance moved / travelled in the direction of the force define the joule;
Energy required to move a weight of 1N (through) a distance of 1 m define power as the rate of work done;
power = work (done)/time or power = energy/time or power = rate of work done define the watt;
Power required to move 1N through a distance of 1m in 1 sec (Rate of doing work) define and use the terms stress, strain,
Young modulus and ultimate tensile strength
(breaking stress);
Stress = force/(cross-sectional) area
Strain = extension/original length
Young modulus = stress/strain / Young modulus is equal to the gradient from stress-strain graph (in the linear region) Ultimate tensile strength = Maximum stress material can withstand (before fracture) define the terms elastic deformation and

plastic deformation of a material;

Elastic: extension (or compression)  force (as long as elastic limit is not exceeded) Plastic: Material does not return to original length / shape/ size (is permanently deformed / longer) when the force / stress is removed Define density

Density = mass/volume or mass per (unit) volume

Derive and apply:
derive the equations of motion for constant
acceleration in a straight line from a velocity
against time graph;

www.thestudentroom.co.uk
Area of triangle = ½ (v-u) t [(v-u) = at]
= ½ a t2
Area of rectangle = ut add the two together
apply the definition of work done to derive the equation for the change in gravitational potential energy;

Work done = force x distance
Force = mass x acceleration
Weight = mass x gravitational field strength
G.P.E. = m x g x h
apply graphical methods to represent
displacement, speed, velocity and
acceleration

apply the equations for constant acceleration in a straight line, including the motion of bodies falling in the Earth’s uniform gravitational field without air resistance

apply the equations of constant acceleration to describe and explain the motion of an object due to a uniform velocity in one direction and a constant acceleration in a perpendicular direction You can talk about ‘large’ deceleration/acceleration but not ‘quick’ apply the equations for constant acceleration and F = ma to analyse the motion of objects

apply the principle of moments to solve
problems, including the human...
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