Question

a student on roller skates glides across a floor with a lunch tray. Total mass is 1.3 kg at waist level 1.1 above the floor from the cash register to her table 23.4 m away how much work is done

Answer 1

$W=F\cdot s\cdot\cos\alpha$

Since the total force acting on the tray is 0 then $W=0$ . Answer