5-2 Resultant force (5.2)

Resultant force (5.2)
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Slide 1: Slide
NatuurkundeMiddelbare schoolhavoLeerjaar 3

This lesson contains 22 slides, with interactive quiz, text slides and 5 videos.

time-iconLesson duration is: 45 min

Items in this lesson

Resultant force (5.2)

Slide 1 - Slide

Slide 2 - Video

Lesson goals:
  • Understand gravitational acceleration.
  • Understand what a driving force is and 
       what a resisting force is.
  • Make calculations with a resultant force. 

Slide 3 - Slide

Gravitational acceleration
- In a lift moving with the same velocity as you
   > it feels as if gravity is absent
- In a lift that is accelerating 
   > it feels as if there is a gravitational force

Therefore you can conclude that you can not seperate acceleration and gravitational force from each other.

Slide 4 - Slide

Slide 5 - Slide

Driving force and resisting force
The two most important resisting forces:
- Air friction 
- Rolling friction
and driving forces are
- gravity
- force of a motor
- pushing force

Slide 6 - Slide

Air friction
Air friction is due to the collision with 
air particles
You can decrease air friction by:
- improving your streamline
- making your frontal cross-section 
   smaller

Slide 7 - Slide

Forces on a car...
             = pushing foce
             = frictional force

The pushin force and frictional force act in the opposite directions.                  is greater than             
therefore                            
is to the right.


Fp
Fr
Fp
Fr
Fres

Slide 8 - Slide

Resultant force causes acceleration
If the pushing force is equal to the frictional force then the resultant force is equal to 0 N


Then there is no acceleration THEREFORE
  • the car stand still OR
  • the car has a constant velocity
Fp=Fr
Fres=0N

Slide 9 - Slide

Resultant force changes velocity
If the pushing force is greater than the frictional force the resultant force is greater than 0 N
               > 
The acceleration will be in the 
direction of the resultant force.
This is also known as Newtons 
first law of motion
    Fp
    Fr

    Slide 10 - Slide

    Resultant force changes velocity
    If there is no pushing force only the frictional force is left and the resultant force acts opposite 
    to the the direction of motion.  

    The car will decelerate
    (or rather have a negative 
    acceleration)

      Slide 11 - Slide

      Slide 12 - Video

      Example

      Slide 13 - Slide

      Slide 14 - Slide

      Slide 15 - Slide

      Slide 16 - Slide

      The resultant force can do three things
      • Accelerate an object (if the resultant force is in the direction fo motion),
      • Decelerate an object (if the resultant force is in the opposite direction of motion)
      • Change direction of an object 
            (when a force comes from the side)

      Slide 17 - Slide

      Slide 18 - Video

      Slide 19 - Video

      Slide 20 - Video

      Now try the following question in your digital method.

      17, 18 and 19

      Slide 21 - Slide

      How did the lesson go? Any questions?

      Slide 22 - Open question