Acar moved at a speed of 50 kilometers/hour. its kinetic energy is 400 joules. if the same car moves at a speed of 100 kilometers/hour

If the car moves at a speed of 50 kilometers an hour and produces 400 joules of kinetic energy then if you twice that speed which is 100 kilometers an hour then you will produce 800 joules of electricity.

air exerts forces on falling objects near earth’s surface.

explanation:

the term 'free falls' refer to object that are falling towards the earth, in a situation in which gravity is the only force acting on the object.

for an object in free fall, the acceleration is constant (g, the gravitational acceleration), and so the velocity of the object constantly increases.

for objects near earth's surface, there is always another force acting on the object: the resistance due to the air. this force is opposed to the direction of fall of the object, and it is proportional to the velocity of the object, so as the object falls down, this force increases up to a point when it balances the force of gravity, and the object continues its motion at constant velocity (called terminal velocity). since in this case gravity is not the only force acting on the object, we are not in a situation of free fall.