Definition of Key Terms
FORM 4 PHYSICS
Chapter 1: Introduction to Physics
Ba quantities are physical quantities that cannot be defined in terms of other physical quantities.
A unit, in measurement, is a quantity adopted as the standard by which any other quantity of the same kind is measured.
Derived quantities are physical quantities derived by combining ba quantity.
A allinonescalar quantity is a quantity which has only magnitude or size.
A vector quantity has both magnitude/size as well as direction.
Systematic errors are cumulative errors that can be corrected.
A zero error aris when the measuring instrument does not start from exactly zero. (systematic error)
Random errors ari from unknown and unpredictable variations in condition, and will produce a different error every time the experiment is repeated.
A parallax error职称英语报名时间 is an error in reading an instrument becau the obrver’s eye and the pointer are not in a line perpendicular to the plane of the scale. (random error)
The consistency of a measuring instrument is its ability to register the same reading when a measurement is repeated.
Accuracy我是冠军英文 is the degree to which a measurement reprents the actual value.
The nsitivity of a measuring instrument is its ability to respond quickly to a small change in the value of a measurement.
Chapter 2: Forces and Motion
Displacement is the distance travelled by an object from its initial position to its final position.
Speed is the distance travelled per unit time.
Velocity is the rate of change of displacement.
Acceleration is defined as the rate of change of velocity.
Inertia is the reluctance of an object to move once it is at rest.
Newton’s first law of motion (Law of inertia) states that every object will continue in its state of uniform velocity or at rest unless it is acted upon by an external force.
The Principle of conrvation of momentum states that the total momentum of a system is constant, if no external force acts on the system.
A force is a push, pull, lift or press
Newton’s cond law of motion states that the rate of change of momentum is directly proportional to the applied force and acts in the direction of the force. (F=ma)
Impul is defined as the product of a force F acting on an object of mass m for the time t.
Impulsive force is the force produced becau of a collision or explosion that happens in a short time interval.
The assuemass of an object is defined as the amount of matter in the object.
澳门科技大学研究生The weight of an object is defined as the force of gravity which is exerted on it.
The gravitational field strength is defined as force per unit mass (N/kg) acting on the object.
Newton’s third law of motion states that for every action there is an equal and opposite reaction.
Frictional force is the force that resists motion when the surface of one object comes into contact with the surface of another.
Equilibrium state is the state of an object in which the resultant force acting on the object is zero.
Work绕口令练口才初学 is done when a force caus an object to move in the distance of the force.
Energy is defined as the capacity to do work.
The Potential energysimon of an object is defined as the energy stored in the object becau if its position or its state.
The Kinetic energy of an object is defined as the energy possd by an object due to its motion.burden
The Principle of conrvation of energy states that energy cannot be created or destroyed. It can be transformed from one form to another, but the total energy in a system is constant.
Power is defined as the rate of work done or the rate of energy transformed.
Elasticity英语在线翻译器 is the property of an object that enables it to return to its original shape and size after an applied external force is removed.
Hooke’s law states that the extension of a spring is directly proportional to the applied force acting on it provided the elastic limit of the spring is not exceeded.
The elastic limit is the maximum applied force whereby the material will return to its original length once the applied force is removed.
Chapter 3: Forces and Motion
Pressure is defined as normal (perpendicular) force per unit area.
Density is defined as the mass per unit volume of a substance.
Pascal’s principlewillson states that when pressure is applied to an enclod fluid, the pressure will be transmitted uniformly in all directions in the liquid.
