Newton's first law is applicable

What was the mistake in Aristotle's idea regarding motion?

Three forces given by vectors $2 \hat{i} + 2 \hat{j}$,$2 \hat{i} - 2 \hat{j}$,and $-4 \hat{i}$ are acting together on a point object at rest. The object moves along the direction:

$A$ rider on horseback falls when the horse starts running all of a sudden because:

Passengers standing in a bus are thrown outwards when the bus takes a sudden turn. This happens because of

We are standing in a stationary bus. When the bus suddenly starts,why are we thrown in the backward direction?