Momentum is defined to be the mass m of an object times its velocity V. The airplane has a mass m0 and travels at velocity V0. The mass and velocity of the airplane change during the flight to values m1 and V1. Let us assume that the mass stays a constant value equal to m.
The weight of the fuel is probably small relative to the weight of the rest of the airplane, especially if we only look at small changes in time. If we were discussing the flight of a baseball , then certainly the mass remains a constant.
But if we were discussing the flight of a bottle rocket , then the mass does not remain a constant and we can only look at changes in momentum. The change in velocity divided by the change in time is the definition of the acceleration a. The second law then reduces to the more familiar product of a mass and an acceleration:. Remember that this relation is only good for objects that have a constant mass. This equation tells us that an object subjected to an external force will accelerate and that the amount of the acceleration is proportional to the size of the force.
The amount of acceleration is also inversely proportional to the mass of the object; for equal forces, a heavier object will experience less acceleration than a lighter object.
Considering the momentum equation, a force causes a change in velocity; and likewise, a change in velocity generates a force. The equation works both ways. Follow-up on this answer. Learn more physics! Related Questions. Still Curious? Can you please explain to me how Newton's Laws of Motion tie into my everyday life. Such as getting ready and going to school. I don't really get how these laws of motion influence everyday life.
And similarly, rows 4 and 5 show that a halving of the mass results in a doubling of the acceleration if force is held constant. Acceleration is inversely proportional to mass. Whatever alteration is made of the net force, the same change will occur with the acceleration.
Double, triple or quadruple the net force, and the acceleration will do the same. On the other hand, whatever alteration is made of the mass, the opposite or inverse change will occur with the acceleration. Double, triple or quadruple the mass, and the acceleration will be one-half, one-third or one-fourth its original value.
As stated above , the direction of the net force is in the same direction as the acceleration. Thus, if the direction of the acceleration is known, then the direction of the net force is also known. Consider the two oil drop diagrams below for an acceleration of a car. From the diagram, determine the direction of the net force that is acting upon the car. Then click the buttons to view the answers. If necessary, review acceleration from the previous unit.
See Answer The net force is to the right since the acceleration is to the right. An object which moves to the right and speeds up has a rightward acceleration. See Answer The net force is to the left since the acceleration is to the left.
An object which moves to the right and slows down has a leftward acceleration. In conclusion, Newton's second law provides the explanation for the behavior of objects upon which the forces do not balance. The law states that unbalanced forces cause objects to accelerate with an acceleration that is directly proportional to the net force and inversely proportional to the mass. Determine the accelerations that result when a N net force is applied to a 3-kg object and then to a 6-kg object.
Determine the mass of the encyclopedia. If the net force is tripled and the mass is doubled, then what is the new acceleration of the sled? If the net force is tripled and the mass is halved, then what is the new acceleration of the sled?
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