Animals know when to migrate because of weather change.

Animals in the Arctic, including reindeer and golden eagles, are migrating earlier due to climate change, say researchers who have gathered a huge amount of data to study the behaviour of 86 Arctic species over the past three decades.

Explanation:

powerful computers now, not then

force is based upon mass and acceleration.the statement is not always true.

it can be explained from newton's second law of motion.

as per newton's second law of motion the rate of change of momentum is directly proportional to the applied force and takes place along the direction of force.

mathematically it can be written as -

                                              ⇒      

here   k is the proportionality constant whose value is 1.

                                                            [a is the acceleration=dv/dt]

hence we see that force not only depends on mass and acceleration but also on velocity and rate of change of mass. force f will depend on mass and acceleration only when mass is constant.

hence the statement that force is based upon mass and acceleration is false.