### Newton's 2nd Law

Calculate acceleration and deceleration using the formula given. Key terms: acceleration The Relationship Between Force and Acceleration: Remember from Therefore, mass is inversely proportional to acceleration. Rules to follow when. The Second Law is concerned with relating acceleration to mass and net force. Thirdly, this acceleration is inversely proportional to the mass of the object. Furthermore, the qualitative relationship between mass and acceleration can be seen by a comparison of the Acceleration is inversely proportional to mass.

The acceleration produced by a force is in the same direction as the force; if several forces act on a body, it is their resultant sumobtained by adding the vectors tail-to-tip, that produces the acceleration. The second law is the most important, and from it all of the basic equations of dynamics can be derived by procedures developed in the calculus.

A simple case is a freely falling body. Neglecting air resistance, the only force acting on the body is its weight acting down, and it produces a downward acceleration equal to the acceleration of gravity, symbolized as g, which has an average value of 9.

**Dependent and Independent Variables - X or Y - Science & Math - Linear, Inverse, Quadratic**

Newton's third law states that the actions of two bodies upon each other are always equal and directly opposite; i. The proposition seems obvious for two bodies in direct contact; the downward force of a book on a table is equal to the upward force of the table on the book. It is also true for gravitational forces; a flying airplane pulls up on the Earth with the same force that the Earth pulls down on the airplane.

The third law is important in statics bodies at rest because it permits the separation of complex structures and machines into simple units that can be analyzed individually with the least number of unknown forces.

At the connections between the units, the force in one member is equal and opposite to the force in the other member. The third law may not hold for electromagnetic forces when the bodies are far apart.

Excerpt from the Encyclopedia Britannica without permission.

Comparing the values in rows 1 and 2, it can be seen that a doubling of the net force results in a doubling of the acceleration if mass is held constant. Similarly, comparing the values in rows 2 and 4 demonstrates that a halving of the net force results in a halving of the acceleration if mass is held constant.

### BBC Bitesize - GCSE Physics (Single Science) - Newton’s Laws – WJEC - Revision 4

Acceleration is directly proportional to net force. Furthermore, the qualitative relationship between mass and acceleration can be seen by a comparison of the numerical values in the above table.

Observe from rows 2 and 3 that a doubling of the mass results in a halving of the acceleration if force is held constant. 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.

## Newton's Second Law

The Direction of the Net Force and Acceleration As stated abovethe 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.