Physics

Problem

A skateboarder moves with speed

v_{S/W}

relative to a moving walkway, which itself moves with speed

v_{W/F}

relative to the airport floor. Using standard subscript notation (object/reference), which expression correctly gives the skateboarder’s speed

v_{S/F}

relative to the floor? a)

v_{S/F}=v_{S/W}+v_{W/F}

v_{S/F}=v_{S/W}-v_{W/F}

v_{S/F}=\dfrac{v_{S/W}+v_{W/F}}{2}

v_{S/F}=v_{S/W}\,v_{W/F}