The correct answer is
Air resistance
In fact, when a ball is in free fall, there are two forces acting on it:
- its weight (force of gravity), acting downward
- the air resistance, acting upward
The effect of the weight is to accelerate the ball, because its direction is the same as the direction of motion of the ball, while the effect of the air resistance is to slow down the ball, because its direction is opposite to that of the motion.
The object will move in the direction of the applied force.
An object that has kinetic energy must be <em>moving</em>.
The formula for an object's kinetic energy is
KE = (1/2) · (the object's mass) · <u><em>(the object's speed)²</em></u>
As you can see from the formula, if the object has no speed, then its kinetic energy is zero. That's why kinetic energy is usually called the "energy of motion", and if an object HAS kinetic energy, then that tells you right away that it must be moving.
Frequency of the wave " the loudness"
Answer:
Explanation:
The momentum of an object is given by 
.
Plugging in values, we have:
.
