When we walk on the ground, we push the ground backward and hence the ground pushes us forward and we change our position. The effect of our force on the Earth is very minute (literally negligible) because it's massive !!
Also we know that each point of an spinning ball has tangential velocities as shown below.
Now imagine that people all around the world decide and get aligned together with their motor cars 🚗 and try to move with some considerable velocity $v$ by pushing the earth back as shown in this figure at the same time.
This time also the force is negligible (since the earth is extremely massive ) , but I think taking the whole population on their motor cars 🚗 and being driven to the same velocity at the same time can cause some effects . So by how much amount (numbers) will it influence the rotation speed of the earth if they all moved at the same time ?
Or conversely, can we increase the rotational speed of the earth by moving in the opposite direction and alter the day - night duration?
Note: the total population of the earth as in September $2020$ is about $7.8 billions$ and take the average mass of them between $50 kg$. Consider they start from rest and accelerate uniformly and travel $100m$ in $2s$ i.e. their acceleration is $50m/s^2$. Take the mass of their cars to be $1000kg$. Assume that all the cars are similar.
I apologise for the edit but otherwise I would have to ask the same question again. Kindly respond to it.