Physics Definition Form 4

PHYSICS DEFINITION 1. 2. 3. 4.

Acceleration is the rate of change of velocity Accuracy is the degree of a measuring instrument to record readings close to the actual value Apparent depth is the distance of image from the surface of the water Archimedes’ principle states that when an object is immersed fully or partially in a fluid, the weight of fluid displaced is equal to the buoyant force experienced by the object 5. Atmospheric pressure is the pressure which results from the collision between the gas molecules of the atmosphere with a body 6. Base quantity is a physical quantity that cannot be defined in other terms of physical quantities 7. Bernoulli’s principle states that in a moving fluid, the points which have a higher velocity will experience a lower pressure whereas points with a lower velocity will experience a higher pressure 8. Boiling point is the temperature at which the substance changes from a liquid to a gaseous state, where the change occurs throughout the liquid 9. Boyle’s law states that for a fixed mass of gas at a fixed temperature, the pressure of gas is inversely proportional to its volume 10.Buoyant force is an upward force acting on an object partially or fully immersed in a fluid 11.Charles’ law states that for a fixed mass of gas, the volume of gas is directly proportional to the absolute temperature of the gas if the pressure is constant 12.Consistency / Precision is the degree of a measuring instrument to record consistent readings for each measurement by the same way 13.Critical angle is the angle of incidence in the optically denser medium for which the angle of refraction, r = 90⁰ 14.Derived quantity is a physical quantity derived by combining base quantities 15.Displacement is the distance in a specific direction 16.Distance is the total path length travelled from one location to another 17.Elastic potential energy is the energy stored in a spring when it is extended or compressed 18.Elasticity is a property of an object to return to its original shape and dimensions after an applied external force is removed 19.Energy is the capacity to do work 20.Focal length is the distance between the centre of the lens to its focal point 21.Free fall occurs when an object is falling under the force of gravity only, without any obstacles 22.Gas pressure occurs when the gas molecules collide with the wall of the container 23.Gravitational acceleration is the acceleration of an object due to the pull of gravitational force 24.Heat capacity is the amount of heat required to change its temperature by 1⁰C 25.Hooke’s law states that the extension of a spring, x is directly proportional to the stretching force acting on it provided the elastic limit of the spring is not exceeded 26.Elastic limit is the maximum stretching force 27.Impulse is the change of momentum 28.Impulsive force is the rate of change of momentum 29.Inertia (Newton’s First Law of Motion) is the tendency of an object to maintain its state of stationary or uniform motion in a straight line unless it is acted upon by an external force 30.Kinetic energy is the energy possessed by an object due to its motion 31.Mass is the amount of matter in an object 32.Melting point is the temperature at which a substance changes its state from solid to liquid

33.The momentum of an object is defined as the product of mass and velocity 34.Pascal’s principle states that when pressure is applied to an enclosed fluid, the pressure will be transferred uniformly throughout the liquid 35.Power is the rate at which work is done 36.Pressure is the force acting normally(perpendicularly) on a unit area 37.Pressure law states that for a fixed mass of gas, the pressure of gas is directly proportional to the absolute temperature of the gas at a constant volume 38.Principle of Conservation 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 39.Real image is an image that can be displayed on a screen 40.Refraction of light is the bending of light ray at the boundary as it travels from one medium to another. 41.Refractive index: When a ray of light travels from the air to a medium, the ratio of sinisinr is the refractive index 42.Resultant force is a single force that represents the combined effect of two of more forces by taking account both the magnitude and the direction of the forces 43.Scalar quantity is a quantity that has magnitude only 44.Sensitivity is the ability of a measuring instrument to detect small changes in the quantity that is being measured. 45.Specific heat capacity is the amount of heat required to increase the temperature of 1kg mass of the substance by 1⁰C 46.Specific latent heat of fusion is the amount of heat required to change 1kg of substance from solid to liquid without any change of temperature of the melting point 47.Specific latent heat of vaporisation is the amount of heat required to change 1kg of substance from liquid to gas without any change of temperature of the melting point 48.Speed is the rate of change of distance 49.Temperature is the degree of hotness of a substance 50.Total internal reflection is the total reflection of a beam of light at the boundary of two mediums when an angle of incidence, i exceeds the critical angle, c 51.Vector quantity is a physical quantity that has magnitude and directions 52.Velocity is the rate of change of displacement 53.Virtual image is an image that can be seen by the observer but cannot be formed on the screen 54.Weight is the force of gravity acting on an object 55.Work done is defined as the product of the force, F and the distance, s in the direction of the force