aidan lifts a box from the floor, carries it across the room, and places it on a high shelf. when is aidan…
aidan lifts a box from the floor, carries it across the room, and places it on a high shelf. when is aidan doing work on the box? (1 point)\nhe does work on the box at no time during this process.\nhe does work only while he carries the box across the room.\nhe does work from the moment he touches the box until he lets it go.\nhe does work as he picks up the box and as he lifts it to the shelf.
Answer
Answer:
He does work as he picks up the box and as he lifts it to the shelf.
Explanation:
Step1: Define work in physics
Work is done when a force is applied over a displacement in the direction of the force, $W = F\times d\times\cos\theta$ (where $W$ is work, $F$ is force, $d$ is displacement and $\theta$ is the angle between force and displacement).
Step2: Analyze picking - up the box
When Aidan picks up the box, he applies an upward force against gravity and the box is displaced upward. So work is done as $\theta = 0^{\circ}$ (force and displacement are in the same direction), and $\cos\theta=1$.
Step3: Analyze carrying the box across the room
When carrying the box across the room, the force applied by Aidan is upward to support the weight of the box, but the displacement is horizontal. Since $\theta = 90^{\circ}$ and $\cos90^{\circ}=0$, no work is done in the physics - sense.
Step4: Analyze lifting the box to the shelf
When lifting the box to the shelf, Aidan applies an upward force and the box has an upward displacement. So work is done as $\theta = 0^{\circ}$ and $\cos\theta = 1$.