Physics
Physics
Problem
Two students, A and B, push a library trolley along a straight corridor. Student A applies a horizontal force of toward the east, while student B pushes with toward the west. A third student, C, can also push the trolley so that it either remains in equilibrium or accelerates. a. (a) Draw a clearly labelled diagram showing the three horizontal forces acting on the trolley and indicate their directions. b. (b) Taking the eastward direction as positive, write the algebraic condition for equilibrium and hence calculate the magnitude and direction of the force that student C must apply so that the trolley remains at rest. c. (c) Instead of following part (b), student C actually applies a force toward the east. Determine the net horizontal force acting on the trolley and its direction. d. (d) The mass of the loaded trolley is . Using the net force found in part (c), calculate the acceleration produced and state its direction.Intuitive explanation
The key here is vector addition of forces — you need to find the net force already acting on the trolley, then figure out what student C must do to either cancel it (equilibrium) or change it (acceleration). Since A and B push in opposite directions along the same line, their forces don't cancel completely; the trolley has a natural tendency to move east. Student C's role is to either restore balance by pushing west, or to reinforce the motion by pushing east, depending on the scenario.
Intuitive explanation
The key here is vector addition of forces — you need to find the net force already acting on the trolley, then figure out what student C must do to either cancel it (equilibrium) or change it (acceleration). Since A and B push in opposite directions along the same line, their forces don't cancel completely; the trolley has a natural tendency to move east. Student C's role is to either restore balance by pushing west, or to reinforce the motion by pushing east, depending on the scenario.