Friction demonstration. Image 2 of 2. The wooden slab and one kilogram mass are being pulled over a smooth wooden table by a newtonmeter, which measures the force required to overcome friction and move the slab. In this case, the newtonmeter shows that a force of 3.7 newtons is required, compared to just 2.2 newtons for the slab alone. This is because increasing the mass increases the frictional force between the slab and the table. For the image of the slab alone being pulled, see A400/120.
Model release not required. Property release not required.