Question

Look at the activity listed here. Reason out whether or not work is done in the light of your understanding of the term 'work'. A green plant is carrying out photosynthesis.

Answer 1

Step 1: Work Done

1. Work is done when the force is applied to displace a body from its original state.
2. Force and displacement are vector quantities.
3. We know that the dot product of two vectors gives a scalar quantity as its result.
4. Thus, work done is a scalar quantity.

If $\overrightarrow{F}$ is the force applied and $\overrightarrow{S}$ is the displacement of the body, then the work done $W$ can be given as,

$W=\overrightarrow{F}·\overrightarrow{S}$

$=FS\cos \theta$

where, $\theta$ is the angle between the direction of force vector and displacement vector.

Step 2: Check if work is done

1. Photosynthesis is the process in which green plants utilize the energy from the sun to make food.
2. So, there is no force applied to the plant which results in no movement.
3. Therefore, the displacement and force are zero.
4. Hence, no work is done by a green plant is carrying out photosynthesis.