1 / 23

Net Force

Net Force. Physics 11 Adv. Comprehension Check. An object has a weight of 12.2N; what is its mass? If you were to take the weight of a 1.0kg object on the moon, what would it be? A 5.00kg wooden crate is slid across a wooden floor; what frictional force is experienced by the crate?

mingan
Download Presentation

Net Force

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript


  1. Net Force Physics 11 Adv

  2. Comprehension Check • An object has a weight of 12.2N; what is its mass? • If you were to take the weight of a 1.0kg object on the moon, what would it be? • A 5.00kg wooden crate is slid across a wooden floor; what frictional force is experienced by the crate? • If a 150N force is applied to a 25kg object, what would its acceleration be?

  3. Comprehension Check • 1.24kg • 1.64N • 9.8N • 6.0m/s2

  4. Putting it All Together • Now that we have considered Newton’s Second Law, you can use that to analyze kinematics problems with less information than we have used previously • We can either use dynamics information to then apply to a kinematic situation or vice versa

  5. A free body diagram will be used in most dynamics problems in order to simplify the situation In a FBD, the object is reduced to a point and forces are drawn starting from the point Free Body Diagrams FN Fa Ff Fg

  6. The Net Force • In most situations, there is more than one force acting on an object at any given time • When we draw the FBD we should label all forces that are acting on an object and also determine which would cancel each other out • Ones that do not completely cancel out will be used to determine the net force

  7. The Net Force • The net force is a vector sum which means that both the magnitude and direction of the forces must be considered • In most situations we consider if Physics 11, the forces we consider will be parallel or anti-parallel

  8. An Example • A 25kg crate is slid from rest across a floor with an applied force 72N applied force. If the coefficient of kinetic friction is .27, determine: • The acceleration of the crate? • The time it would take to slide the crate 5.0m across the floor.

  9. FBD FN=250N Fa=72N Ff=? Fg=-250N

  10. Use the frictional force equation to determine the magnitude of the frictional force

  11. The net force is the sum of the forces (acting parallel or anti-parallel)

  12. Use Newton’s Second Law to solve for the acceleration

  13. Use kinematics to solve for the time taken to cross the floor

  14. Pushing or Pulling a Sled – Which is Better?

  15. Pushing a Sled • A child of 35kg is sitting on a sled that has a coefficient of kinetic friction of 0.10 with the snow. If the parent who is pushing the sled pushes down with an angle of 25°, with what force do they need to push to keep the child and sled sliding with a constant velocity?

  16. FBD FN Fa Ff Fg

  17. Break Applied Force into Components Fax Fay Fa

  18. Consider x and y independently

  19. Pulling a Sled • A child of 35kg is sitting on a sled that has a coefficient of kinetic friction of 0.10 with the snow. If the parent who is pulling the sled pulls up with an angle of 25°, with what force do they need to pull to keep the child and sled sliding with a constant velocity?

  20. FBD FN Fa Ff Fg

  21. Break Applied Force into Components Fa Fay Fax

  22. Consider x and y independently

  23. Practice Problems • Page 168 • Questions 4-8 • Page 170 • 9 - 13 • Physics 20 • Page 108 • 1-10 and 17

More Related