Measurements Length Length is a measure of how long an object is. The standard SI (international system of units) of length is the meter (m) We can measure the length using a meter tape. 1 km = 1000 m 1 m = 10 dm = 100 cm = 1000 mm Mass Mass is the amount of matter in an object & it is typically fixed (doesn’t change). The SI unit of mass is the Kilogram (kg) We can measure mass by using a balance. 1kg = 1000 g 1 ton = 1000 kg Weight Weight is a force that measures the pull of gravity on an object. Weight is not constant, it changes with location. Weight is measured in Newton (N) Weight = mass X gravity N.B gravity on earth is constant (9.8 m/𝒔𝟐 ) Time: Time is a measure of how long it takes to do something The SI unit of time is the seconds (s) We can measure time by using a stopwatch. 1 minute = 60 sec 1 hour = 60 min = 3600 sec Temperature Temperature is a measure of how hot an object is. The SI unit of temperature is Kelvin (K) We can measure temperature using thermometer. K= ˚C + 273 Volume The volume of an object is the amount of space and object occupies. It is measure in 𝒎𝟑 Volume of a regular shape: Area of base X height Volume of a rectangular block= Length X width X height Volume of a liquid can be found by pouring it into a measuring cylinder and read the volume from the scale. Volume of an irregular shape: An irregular solid doesn’t have sides that can be easily measured. Water is poured into a measuring cylinder until it is half full. Volume of water is measured. The solid is added to the water gently. Volume of water is read again. The difference in water volume before and after adding the solid is the solid’s volume Density Density is the mass of an object per unit volume. It is measured in kg/𝑚3 Density = Mass / volume 1. Weigh the solid using balance. 2. Calculate its volume 3. Divide its mass by its volume