Review Concepts

Exam III

Chapter 2 – Newton’s First Law of Motion – Inertia

Newton's First Law – An object continues to move as it has been moving, unless acted upon by a force.

Inertia - The property of an object that resists changes of motion. Measured by the mass.

 

Chapter 3 – Linear Motion

Speed - The distance traveled per time.

Speed = Distance /Time

Velocity – The vector equivalent of speed.

Velocity needs speed + direction

Acceleration - The rate at which velocity changes with time; the change in velocity may be in magnitude or direction or both.

General Motion Equations:

distance = d = (initial velocity) X time + ½(acceleration) X (time)2 = v0 + ½ at2

velocity = initial velocity + (acceleration) X (time) = v0 + at

 

Free Fall – Falling under the influence of gravity ONLY. Neglects air resistance.

During free fall….

acceleration = g = 9.8 m/s2 » 10 m/s2

velocity = v = g t » 10t

distance traveled = ½ gt2 » 5t2

Review page 33.

Chapter 4 - Newton's Second Law of Motion

Newton’s Second Law – the acceleration of an object is given by

a = SF/m

or,

SF = ma

Mass - The quantity of matter in an object. It is the measurement of the inertia or sluggishness that an object exhibits in response to any effort made to start it, stop it, or changes in any way its state of motion.

Weight - The force due to gravity on an object.

Kilogram - A fundamental unit of mass (symbol kg).

Newton - A unit of force. One Newton (symbol N) is the force that will give an object of mass 1 kg an acceleration of 1 m/s2.

Force - Any influence that can cause an object to be accelerated; measured in Newtons in the metric system and pounds in the British system.

Friction - The resistive forces that arise to oppose the motion of an object.

Terminal speed - The speed at which the acceleration of a falling object terminates (becomes zero) because air resistance balances the weight.

Chapter 5 – Newton’s Third Law of Motion

Newton's Third Law - For every action there is an equal and opposite reaction.

Mechanical equilibrium - The state of an object for which all forces cancel to zero and no acceleration occurs.

Vector quantity - A quantity that has both magnitude and direction. Examples of vector quantities are force, velocity, and acceleration.

Scalar quantity - A quantity that has magnitude, but not direction. Examples of scalar quantities are mass and speed.

Vector - An arrow drawn to scale used to represent a vector quantity.

Resultant - The net result of a combination of two or more vectors.

 

Chapter 5 – Momentum

Newton’s Second Law can be expressed as

SF = Dp/Dt

or,

Dp = (SF) X (Dt)

which is called impulse.

When SF = 0, then Dp must be zero too and that means Momentum is Conserved!

Inelastic Collisions – Conserve momentum only

Elastic Collisions – Conserve both momentum and energy