Practise Edexcel A-Level Physics gravitational field strength and weight through W=mg calculations, mass conversions and density-based weight estimates.
When an object is in contact with a horizontal surface, there is a maximum frictional force F between the object and the surface before sliding occurs.
F is given by the equation
where is a constant and N is the normal contact force between the object and the surface.
A student investigated this relationship for a rubber block on a concrete surface. She set up the apparatus as shown in the diagram.
The student varied the mass m placed on top of the rubber block and determined corresponding values of F. Her results are shown in the table.
Explain how the values of N are calculated.