INTRO TO PHYSICSF3

Forces Part 3

Gravity, Falling Objects,Projectile Motion

and Satellite Motion

Chapters 4.5-4.6; 4.8-4.9; 5.4-5.6, 6.6-6.7, 10.3-10.4, 11.1, 13.4-13.6, 13.8; 14.1-14.6

Key Terms

Free Fall Motion / Free Fall Equations / Projectile Motion
g-- Acceleration due to gravity (9.8 m/s2) / How fast v = gt / Projectile
Weight to mass ratio (F/m) / How far d = ½ gt2 / Horizontal and vertical components of motion
Air resistance (drag) / How long (time)
t = √ 2d/g / Parabola
Trajectory
Terminal velocity / Free fall / Launch angle
Gravity / Satellite Motion
Law of Universal Gravitation
Fg = G x m1m2/d2
G is the gravitational constant (6.667 x 10-11) / Orbit (circular vs. elliptical) and Kepler’s Laws / Torque
Mass vs. distance / Escape velocity
Inverse square law / Centripetal force
g-force / Inertial (tangential) velocity

Essential Question

  • How do you determine the motion of falling objects?

Learning Targets

LT 1I can calculate how fast, how far and how long an object will fall, neglecting air resistance.

LT 2I can explain why all objects, neglecting air resistance, fall at the same rate.

LT 3I can explain freefall and identify when terminal velocity occurs for falling objects.

LT 4I can explain the two factors that influence the amount of air resistance a falling object experiences, and analyze the forces interacting on a falling object to determine its motion.

LT 5I can interpret motion graphs for falling objects.

LT 6I can define gravity and predict how changes in mass and distance will influence gravity.

LT 7I can calculate the gravitational force between any two objects using Newton’s Law of Universal Gravitation.

LT 8I can explain how a projectile represents a moving object having two different components of motion in two dimensions.

LT 9I can identify which launch angle causes the projectile to travel the farthest horizontally.

LT 9I can explain how the planets and other satellites stay in motion and the role of centripetal force on this motion.

LT 10I can identify the significance of Kepler’s Laws and the orbit of planets.

LT 11I can explain why astronauts in orbit experience apparent weightlessness (g-forces).

LT 12I can explain and demonstrate torque.

LT 13I can compare and contrast the nature of motion and forces on the Earth and Moon.

Learning Targets

Lesson 1

I can calculate the gravitational force between any two objects using Newton’s Law of Universal Gravitation, and can predict how changes in mass and distance will influence gravity.

Lesson 2

I can explain g-forces and why they occur.

Lesson 3

I can explain how a projectile represents a moving object having two components of motion.

Lesson 4

I can explain how the planets and other satellites stay in motion and the role of centripetal force on this motion.

Lesson 5

I can explain free fall and why objects accelerate as they fall.

Lesson 6

I can explain why all objects, neglecting air resistance, fall at the same rate.

Lesson 7

I can calculate how fast, how far and how long an object will fall, neglecting air resistance.

Lesson 8

I can explain the two factors that influence the amount of air resistance a falling object experiences, and the forces interacting on falling objects.

Lesson 9

I can analyze motion graphs of falling objects.

Lesson 10

I can explain gravity’s role in the formation of black holes and tides.

Falling Objects Unit Objectives

  1. Solve free fall motion problems.
  2. Explain how weight and force of gravity are related.
  3. Explain air resistance and what it depends upon.
  4. Explain why objects fall on the Earth and Moon differently.
  5. Explain the effects of air resistance on falling objects.
  6. Explain why a lighter object and heavier object fall at the same rate.
  7. Explain terminal speed and velocity.
  8. Use motion graphs and free-body diagrams to illustrate falling objects.
  9. Explain how acceleration rates change for falling objects as they approach terminal velocity.
  10. Evaluate differences in how object fall through the atmosphere.
  11. Explain the two components of projectile motion.
  12. Explain how projectiles move and predict paths
  13. Evaluate motion graphs to identify free-fall vs. terminal velocity

Understand how and why objects accelerate when they fall, and at which rate.

Understand how differences of gravity and atmosphere on the Earth and Moon influence how objects fall.

Understand how to calculate how fast a falling object moves, how far a falling object travels and how long it takes for a falling object to fall a certain distance.

Understand the factors that influence air resistance.

Understand the velocity of a skydiver during free-fall and after the parachute is pulled.

Understandwhat can happen when objects move at extreme speeds in the atmosphere.

Understand the composition of the atmosphere.

Understand the relationship between forces and falling objects.

Understand which two components of motion cause the curved path of a projectile.

Understand the relationship between horizontal motion and inertia for projectiles.

Understand the how the weight to mass ratio proves why all objects fall at the same rate neglecting air resistance.

Understand the physics of a meteoroids and comets moving through space and then our atmosphere.

Intro to PhysicsName ______

Reading Guide

Ch. 6.7Falling and Air Resistance

Falling and Air Resistance

  1. What can you say about the accelerations of a feather and a coin in a vacuum? Would this be different on the Moon? Why or why not?
  1. How does air resistance influence the net force acting on falling objects?
  1. What is the net force of an object that is in freefall?
  1. Which two factors is air resistance force dependent upon? How can this be expressed in a relationship?
  1. Explain two ways that air resistance force can be reduced.
  1. Answer the THINK question on page 95.

Terminal Velocity

  1. Define terminal speed and terminal velocity.
  1. Which two forces are balanced at terminal velocity?
  2. Draw a free body diagram of a 35 N object in free fall and at terminal velocity.
  1. Why does a feather reach terminal velocity so quickly?
  1. What is the terminal velocity for a skydiver? (Convert this to miles per hour [1 km = 0.62 mi]
  1. Explain the difference between zero acceleration and zero velocity.
  1. How can the terminal speed of a skydiver change as a skydiver falls?
  1. What is the terminal velocity for a skydiver with their parachute deployed?
  1. Why is it that a baseball and tennis ball fall at the same rate when dropped from a short height, but fall differently when dropped from a much greater height?