AP Monday 13 Sep

Learning Objective: Correct Free Response  More Free Body

Journal:

1. What is the relationship between unbalanced forces, acceleration, net force and D velocity?

2. If velocity is zero, then acceleration must be zero too. Explain what you think.

Quiz:  (Free Response question)

Notes:

1. On planet Z, the standard unit of length is the foose. Kellie the Astronaut is 1.90 m tall on earth. She lands on planet Z and is measured to be 94 foose tall. Her partner Daye is 88 foose tall. How tall is Daye  on earth?

            a. 1.55 m

            b. 1.78 m

            c. 1.93 m

            d. 2.03 m

2. a. What is the area of a square with sides of 2.0m?

   b. What is  the area of a square with sides of 4.0m?

   c. What is  the area of a square with sides of 6.0m?

    d. What is the relationship of length to area as you increase the length?

3. If the force on an object from Earth’s gravitational field is 90 Newtons at a distance of 1x10¹⁰m away from Earth’s center,

a. Predict what would be the force of gravity on that object is it is moved twice as far away (2x10¹⁰m away)?

b . Predict what would be the force of gravity on that object is it is moved to 3x10¹⁰m away)?

1. b

2. a. 24m²

    b. 96m²

   c.  216m²

   b. L = a²

^{3. a. 1/2 as much or 45 N}

     ^{b. 1/9 as much or 10 N}

   Balanced forces:

Block moving at constant velocity.

I

 

 

 

 

 

Unbalanced force:

In the statement of Newton's first law, the unbalanced force refers to that force which does not become completely balanced (or canceled) by the other individual forces. If either all the vertical forces (up and down) do not cancel each other and/or all horizontal forces do not cancel each other, then an unbalanced force exists. The existence of an unbalanced force for a given situation can be quickly realized by looking at the free-body diagram for that situation. Free-body diagrams for three situations are shown below. What is the acceleration in each case?

As ball rolls down the ramp, what is happening to the motion and why?

What is the Normal and the Net Force in each of the following cases?

               b. Acceleration of - 8 m/s²

a. F_net =  ma   -->   (20)(4) = 80N  

 Normal - Weight = F_net   --> N - 200 = 80

N  = 280

b. F_net =  ma   -->   (20)(-8) = -160N 

Weight - Normal = F_net   --> 200 - Normal = -160

N  = -40N

Newton's second law of motion pertains to the behavior of objects for which all existing forces are not balanced. The second law states that the acceleration of an object is dependent upon two variables - 1.   net force acting upon the object, and

2.  inversely upon the mass of the object.

2nd Law Quiz:

http://www.batesville.k12.in.us/Physics/PhyNet/Mechanics/Newton2/Second_Law_Quiz.html#concept%20quiz

http://www.batesville.k12.in.us/Physics/PhyNet/Mechanics/Newton2/Second_Law_Quiz.html#numerical%20quiz