Question

Two students are simultaneously pushing a glider on a frictionless air track, each with a constant horizontal force. In the examples that follow, assume that student 1 always does positive work on the block (Ws, > 0 and that student 2 always does negative work (Ws2 0 Suppose that the glider moves to the left with constant speed. 1. In which direction is each student pushing the block? Use the definition of work to answer

Answer 1

Answer:

The student 1 pushes to the left, the student 2 pushed to the right

Explanation:

Mechanical Work

The work done by a force F on an object moving a distance X and making an angle $\theta$ with the force is given by

$W=F.X.cos\theta$

If the force and the distance point in the same direction, the angle is 0 and the work is positive.

If the force and the distance point in opposite directions, the angle is 180° and the work is negative.

We know the glider moves to the left and the student 1 always does positive work, thus he must be pushing the block to the left to have the same direction.

The same can be applied to the second student who does a negative work when the block goes to the left, so he must be pushing to the right direction.

Summary: The student 1 pushes to the left, the student 2 pushed to the right