joshua programs a robotic arm to place a block in a box by following the sequence of commands in the…

joshua programs a robotic arm to place a block in a box by following the sequence of commands in the table.\n| step | command |\n| ---- | ---- |\n| 1 | grip block |\n| 2 | lift block ten centimeters |\n| 3 | hold for twenty seconds |\n| 4 | release block |\nduring which step does the robotic arm do work on the block?\nstep 1\nstep 2\nstep 3\nstep 4

joshua programs a robotic arm to place a block in a box by following the sequence of commands in the table.\n| step | command |\n| ---- | ---- |\n| 1 | grip block |\n| 2 | lift block ten centimeters |\n| 3 | hold for twenty seconds |\n| 4 | release block |\nduring which step does the robotic arm do work on the block?\nstep 1\nstep 2\nstep 3\nstep 4

Answer

Explanation:

Step1: Recall work - definition

Work is done when a force causes a displacement in the direction of the force, $W = F\times d\times\cos\theta$ (where $\theta$ is the angle between force and displacement).

Step2: Analyze Step 1

In Step 1 (Grip block), there is no displacement of the block, so work done is 0.

Step3: Analyze Step 2

In Step 2 (Lift block ten centimeters), a force is applied by the robotic - arm to lift the block against gravity and the block is displaced in the direction of the force. So work is done.

Step4: Analyze Step 3

In Step 3 (Hold for twenty seconds), the block is stationary, so there is no displacement and work done is 0.

Step5: Analyze Step 4

In Step 4 (Release block), the robotic - arm just stops applying the holding force, there is no force applied by the arm causing a displacement, so work done is 0.

Answer:

B. Step 2