Created by nikeishabk
almost 10 years ago


Question  Answer 
Scalar  A quantity that has Magnitude only 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). 
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  the rate of change of distance. 
Acceleration  The rate of change of velocity/The gradient of a velocity vs time graph. (= change in velocity / time taken). 
The Newton  The (net) force which gives a mass of 1kg an acceleration of 1 ms2. 
Torque of a Couple  One of forces × perpendicular distance (between forces) (Not force x perpendicular distance). 
Moment of a force  Moment = force x perpendicular distance from pivot / axis / point. 
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  Stopping distance: Thinking distance + braking distance. 
Work done by a Force  Work done = force x distance moved / travelled in the direction of the force. 
Joule  Energy required to move a weight of 1N (through) a distance of 1 m. 
Power  rate of work done  Power = work (done)/time or power = energy/time or power = rate of work done. 
Watt  Power required to move 1N through a distance of 1m in 1 sec (Rate of doing work). 
Stress  Force/(crosssectional) area. 
Strain  Extension/original length. 
Young's Modulus  Stress/strain. Young modulus is equal to the gradient from stressstrain graph (in the linear region). 
Ultimate Tensile Strength (UTS)  Ultimate tensile strength = Maximum stress material can withstand (before fracture). 
Elastic Deformation  Extension (or compression) force (as long as elastic limit is not exceeded). 
Plastic Deformation  Material does not return to original length / shape/ size (is permanently deformed / longer) when the force / stress is removed. 
Density  Mass/volume or mass per (unit) volume. 
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