newton's first law of motion

FORCE

• Definition: A force is any push or pull that causes a change in the motion of an object.

• Types of Forces: Push and pull are opposite forces.

  • PUSH: Applied in one direction to move an object away.

  • PULL: Applied to draw an object towards oneself.

TYPES OF FORCE

• Contact Force: Exists when two or more surfaces or media touch and interact.

• Non-Contact Force: Present in nature always and does not require human intervention to exist.

MOTION

• Speed: The length of distance traveled in a certain amount of time.

• Velocity: The rate of change of displacement in a specified direction.

• Acceleration: The rate of change of velocity caused by an unbalanced force.

SPEED

• Example: A car traveling at a speed of 100 mph.

VELOCITY

• Example: A car traveling at a velocity of 100 mph to the East.

ACCELERATION

• Example: A car slows down at a stop sign and then accelerates again.

NEWTON'S FIRST LAW OF MOTION: LAW OF INERTIA

• Law of Inertia: An object will remain at rest or in uniform motion unless acted on by an unbalanced force.

• Inertia: The resistance of an object to change in its state of motion. It is mass-dependent.

  • Massive objects exhibit greater inertia, and smaller objects exhibit lesser inertia.

• Mass: The amount of matter in an object, measured in kilograms (kg).

• Weight: The amount of gravitational force acting on an object, measured in newtons (N).

• Forces acting on an object at rest include normal force and gravitational force.

SUMMARY OF THE FIRST LAW

• An object at rest will remain at rest, and an object in motion will continue in motion unless influenced by an unbalanced force.

NEWTON'S SECOND LAW OF MOTION: LAW OF ACCELERATION

• Definition: The acceleration of an object is directly proportional to the net force acting upon it and inversely proportional to its mass.

• Greater mass requires a greater force to achieve acceleration.

FORMULAS

• Newton's Second Law: F = ma

• Rearranged formulas:

  • a = F/m

  • m = F/a

• 1 Newton (N) is equivalent to 1 kg·m/s².

• Weight calculation: W = mg where g = 9.8 m/s².

SAMPLE PROBLEMS

1. To find the net force required for a rocket to achieve an acceleration of 70 m/s² with a mass of 45,000 kg.

2. To calculate the acceleration of a 0.60 kg ball hit with a force of 12 N.

3. To determine the mass of an encyclopedia when a net force of 15 N causes an acceleration of 5 m/s².

4. To solve for the mass of an object accelerating at 2.25 m/s² with a force of 7.80 N applied.

5. To find the amount of force needed for an object of mass 1500 g to accelerate at 10.0 m/s².

6. To calculate the acceleration of a 6.3 kg object with a force of 7.1 N applied to it.

NEWTON'S THIRD LAW OF MOTION: LAW OF INTERACTION

• Principle: Whenever two objects (A and B) interact, they exert forces on each other.

• Reaction Example: In every action, there is an equal and opposite reaction.

• Interaction Examples: The flying motion of birds and the bouncing of a ball.