PhysicsFirst Semester Exam Review

First Semester Exam Review

• 70 questions• 70 points total• Class work, Homework, Quiz = 80%• Exam = 20% • Duration:3 hours

First Semester Exam Review

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General Topics

• Speed – Distance - Time• Velocity • Vectors• Acceleration• Friction• Gravity / Free fall• Potential Energy• Kinetic Energy• Work• Power• Mechanical Advantage• Momentum• Newton’s Laws (First, Inertia, Second, and Third)• Collision• Bounce

TopicsSpeed – Distance – Time

Sample

Velocity

Speed with direction

Example

Acceleration

Vf – Vi

t

VectorsSample

Friction

There are four main types of friction:

Static

Sliding

Rolling

Fluid

Gravity / Free fallSample

Rate of acceleration due to free fall is 9.8m/s

Instantaneous speed = v

Gravity = g

Time = t

v=gt

The change in speed each second is the same whether the ball is going upwards or downwards.

Free Fall

0s

1s

3s

2s 4s

5s

6s

7s

Initial Velocity = 30m/s

Potential Energy

An object may store energy by virtue of its potential.

The energy that is stored and held in readiness is called potential energy (PE) because in the store state it has the potential for doing work

Kinetic Energy

If an object is moving then it is capable of doing work. It has energy of motion, or Kinetic energy (KE).

The kinetic energy of an objects depends on the mass of the object as well as its speed.

Conservation of Energy

The law of conservation of energy states that energy may neither be created nor destroyed.

Work donePower =

Time interval

One well-known power unit is horse-power (hp). James Watt, who made the steam engine practical, measured the rate at which a horse could work and found it to be about 550 ft-lb / sec

Mechanical Advantage

Mechanical advantage has a value:

Momentum

You can calculate momentum by multiplying an objects mass (kilograms) and its velocity in (meters per second).

Momentum is measured in units of kilogram-meter per second

Mass x Velocity = kg.m/s

Newton’s First Law

The state of motion of an object does not change as long as the net force acting on the object is zero

An object at rest tends to stay at rest and an object in motion tends to stay in motion with the same speed and in the same direction unless acted upon by an unbalance force

Newton’s Second Law

The acceleration of an object is equal to the net force acting on it divided by the objects mass.

Example

Double the mass of an object half the acceleration.

Half the mass double the acceleration

Newton’s Third Law

Whenever an object exerts a force on a second object, the second object exerts an equal and opposite force on the first object.

"For every action, there is an equal and opposite reaction."

ACTION - REACTION

Newton’s Inertia

Newton's first law of motion - sometimes referred to as the "law of inertia."

Inertia is the tendency of an object to resist a change in motion.

“every object continues in a state of rest, or of motion in a straight line at a constant speed, unless it is compelled to change that state by forces exerted upon it.”

Collision

Elastic collisions occur when the colliding objects bounce off of each other. This typically occurs when you have colliding objects which are very hard or bouncy and kinetic energy is conserved.

Collision

Inelastic collisions occur when two objects collide and kinetic energy is not conserved.

In this type of collision some of the initial kinetic energy is converted into other types of energy (heat, sound, etc.), which is why kinetic energy is NOT conserved in an inelastic collision.

Bounce

If an object is acted on by equal and opposite forces then it will be in equilibrium, and it's acceleration or velocity (and so direction as well) will not be changed.

So when a ball bounces, it exerts a force on the floor, which matches the magnitude of the force in the opposite direction (the ball is bouncing perfectly vertical), up