Machines
Machines Machines are devices that enables us to do work more easily. Simple machine such as levers, pulleys, gears and screws are used to build more complicated machines. For example, a crane is a combination of pulleys, gears and levers. Work In science, work is done when a force moves. For example, when you lift…
Physical Quantities and Measurement
Physical Quantities A physical quantity is anything that can be measured. Physical quantities can be divided into base quantities and derived quantities. Base quantities are those quantities which are distinct in nature and cannot be defined by other quantities. Derived quantities are those whose definitions are based on other physical quantities (base quantities). Some base…
Density
Density Density of a substance is the mass per unit volume of a substance. We are used to saying things like a bag of cement is heavier than a bag of feathers. This is true and the reason is that a bag that holds 50kg of cement can hold less than 10kg of feathers. In…
Forces
Force A force is a push or a pull. Forces causes objects to accelerate, change direction, or change shape. The strength of a force is measured in Newtons ( N). Forces can be grouped into two types, contact forces and non contact forces. Contact forces act on objects they are in contact with and non…