Why does Time pass more slowly for observers traveling at high speeds or near a massive body.

PASS Content Standard 2.1 Objects change their motion only when a net force is applied. Laws of motion are used to determine the effects of forces on the motion of objects.

Motion - 12 min

Earth rotates on its axis at 1,100 mph Earth orbits the Sun at 68,000 mph

The whole galaxy rotates at 490,000 mph

Two Dimensional World

Speed - 4 min

Speed= distance time

Speed= distance time A snail crawls 10 feet in 5 minutes. What is the speed of the snail? = 10 feet 5 minutes =2 feet/min

Average speed= total distance total time

Average speed= total distance total time A boy runs 1 mile in 6 minutes, rests for 2 minutes, then walks 1 mile in 12 minutes. What is his average speed? = 1 mile + 1 mile 20 minutes = 2 miles 20 minutes

Distance (meters) Time (seconds)

is a vector quantity because it has both speed and direction.

Vectors - 12 min

All these planes have the same speed. How is their velocity different?

The length of the line represents the quantity (speed) and the arrow indicates the direction. Add vectors head to tail.

Direction is indicated by compass degrees

The magnitude of the speed is indicated by the measured length (scale) of the line.

0o0o 90 o 180 o 270 o An airplane is flying 200 mph at 50 o. Wind velocity is 50 mph at 270 o. What is the velocity of the plane?

0o0o 90 o 180 o 270 o

0o0o 90 o 180 o 270 o

0o0o 90 o 180 o 270 o

0o0o 90 o 180 o 270 o

0o0o 90 o 180 o 270 o

Acceleration = Velocity (final) - Velocity (original) time

Acceleration = Velocity (final) - Velocity (original) time A car traveling at 60 mph accelerates to 90 mph in 3 seconds. What is the car’s acceleration? = 90 mph - 60 mph 3 seconds = 30 mph 3 seconds = 10 mph/second

Acceleration = Velocity (final) - Velocity (original) time A car traveling at 60 mph slams on the breaks to avoid hitting a deer. The car comes to a safe stop 6 seconds after applying the breaks. What is the car’s acceleration? = 0 mph - 60 mph 6 seconds = - 60 mph 6 seconds = - 10 miles per hour per second

Acceleration toward the center of a circular path.

For an object to travel in a curved path, some force must be accelerating it toward the center of the circle.

Force provided by engine Acceleration provided by tires

What happens if the accelerating force is removed?

An apparent force that appears only in rotating frames of reference.

This “false” force appears to push away from the center of the circular path.

Aristotle and Newton had different ideas about forces and motion. Aristotle's idea: For an object to move at a constant speed, a constant force must be applied. Newton's idea: An object moving at a constant speed will continue at that speed without additional force being applied.

Forces & motion - 6 min

Produce NO Motion

Produce Motion

Sliding - two solid surfaces rubbing against each other. Rolling - an object rolling over a surface. Fluid - an object moving through a fluid.

Newton’s Laws - 5 min

An object at rest will remain at rest, and a moving object will remain at a constant velocity unless acted on by unbalanced forces.

Force = mass X acceleration F = Ma

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

Rockets - 6 min

Momentum - 8 min

Does a long pendulum swing faster than a short one?

Does a heavy pendulum swing faster than a light one?

The total momentum of any group of objects remains the same unless acted on by outside forces.

Elastic - occur when both momentum and kinetic energy are conserved. Inelastic - occur when momentum is conserved, but kinetic energy is not.

M 1 V 1 = M 2 V 2 Before After

Colliding objects have same mass Elastic Collision

Heavy object strikes light object Elastic Collision

Light object strikes heavy object Elastic Collision

Inelastic Collision Colliding objects have same mass

Rollercoasters - 24 min

Units of Force are Newtons Units of Distance are Meters Newton Meters = Joules

Units of Work are Joules Joules per second = Watts Power is the rate at which work is done.

Work & Power - 15 min

power - 2 min

1 Horsepower is equal to Watts or 550 ft lb/sec

Climbing cars - 24 min

The effort force is applied to a machine.

The resistance force is applied by a machine.

The number of times a machine multiplies the effort force.

Work output Work input X 100

Da Vinci - 8 min

Work is made easier because the effort force moves over a greater distance.

Inclined Plane - 2 min

Force is multiplied since it is applied to a wide area and exerted over a small area.

Wedge - 2 min

Multiplies an effort force by acting through a long effort distance.

Screw - 1 min

A bar which can move freely around a fixed position, or fulcrum.

Levers - 3 min

The Fulcrum is between the Effort Force and the Resistance force

Multiplies Effort Force and changes its direction

The Resistance is between the Effort Force and the Fulcrum

Multiplies the Effort Force but does not change its direction

The Effort force is between the Resistance Force and the Fulcrum

Does not multiply the Effort Force

Direction of the Effort Force is changed. Mechanical Advantage = 0

Direction of the Effort Force is not changed. Mechanical Advantage = 1

Direction of the Effort Force is changed. Mechanical Advantage is equal to the number of supporting ropes.

Pulleys - 1 min

A fixed pulley does not have a mechanical advantage. Fixed pulleys only change the direction of the force.

A movable pulley does have a mechanical advantage. The effort force is in the direction of the movement of the resistance.

Two wheels of different sizes connected - the axle being the smaller wheel.

Wheel & Axle - 1 min

Worm Gear

Compound Machines - 4 min