Thursday 17 Sep:

 

Key Concept(s) Today:  Motion equations

 

Journal: Q's

  • Inertia deals with the state of motion (at rest or in motion).

 

  • If you add two vectors (3 m and 5 m), which of the following can the magnitude of the resultant vector be (explain):

a.  8 m only

b.  2 m and 8 m only

c. Something else, explain.

 

 

 

 

 

Vector Worksheet

1. If vector A = 5 m north and vector B = 10 m east, find the resultant of vector (polar form).

 

 

2.      300 @ 2400   find rectangular form.

 

 

 

3. Find speed, displacement & velocity of the following

 

East @ 20km/hr for 1.5 hours,

South @ 20km/hr for 1 hours,

North @ 30km/hr for 2 hours,

West @ 40km/hr for 2 hours,

North @ 20km/hr for 0.5 hours

 

 

 

 

 

 

 

 

 

 

4. What is the result (polar) of the following three vectors:
                    

 

  

 


 

      100 @ 900

 

                                                                 90 @ 00

 

                                                                      200 @ 340 0

5. What is the result (polar) of the following three vectors:

 


 

                                                                                      100 @ 600

 

               200 @ 1800

 

 

                                                                                                 100 @ 3150

 

 

6. A person bikes for 3 hours. Their displacement is 50 km ∟1200  Provide a logical path (x and y) that the would be at for 1st , 2nd, and 3 hour in order to arrive at this displacement

 

x1  =                     y1  =

 

x2  =                     y2  =

 

x3  =                     y3  =

 

 

 

 

 

 

 

 

 

 

 

 

 Answers:

 

  1. If vector A = 5 m north and vector B = 10 m east

Ans =   11.2m ∟26.50

 

  1. 300 @ 2400 

Ans =   x = -150    y = -260

 

3.  East @ 20km/hr for 1.5 hours,

   South @ 20km/hr for 1 hours,

   North @ 30km/hr for 2 hours,

   West @ 40km/hr for 2 hours,

   North @ 20km/hr for 0.5 hours

 

                  Speed  = 28.6 km/hr

            Displacement = 70.7 ∟1350  km

          Velocity =    10.1 ∟1350  km/hr

 

4.   280 ∟6.60

 


 

      100 @ 900

     90 @ 00

                                                                                 200 @ 340 0

5.  80.9 ∟168.70

 100 @ 600

 

               200 @ 1800

    100 @ 3150

 

6. 50 km ∟1200 

x =  - 25    y = 43.3

 

 

 

 

 

 

Practice Problems:

 

 

1. A golf ball is hit with an initial speed of 100m/s.  (At a 700 angle)  (no air friction)

 

            a. How long (t) to the Apex?

            b. How high (m) to the Apex?

            c. It hit the green ----- m away

 

 

                       

a. Time to apex:  (depends only on vertical velocity)

 

                     Vy = (Sin q)(100) = (Sin 70)(100) = 94m/s à /10 à 9.4s  to apex

 

 

b) Heighty = Vot + ½ at2 

               Heighty = (94)(9.4)+ .5 (-10)(9.42)

                Heighty = (884) + (- 442)  = 442m

 

       c) Horz V = (Cos q)(100)   

                                                Vx  à  (Cos 70)(100) à 34 m/s

             

dist =  v (2t)    

        = (34)(18.8)  =   640m

 

2.    An object is thrown upward with a speed of 20 m/s on the surface of planet "E"  where the acceleration of gravity is 4.0 m/s2.  How long does it take for the object to reach maximum height?

 

Vf = Vo + at  

0 = 20 + (-4)(t)  à t = 5.0s

 

 

 

 

 

 

 

 

Free-Body Exercises: Linear Motion

In each case the rock is acted on by one or more forces. All drawings are in a vertical plane, and friction is negligible except where noted. Draw accurate free-body diagrams showing all forces acting on the rock. LM-1 is done as an example, using the "parallelogram" method. For convenience, you may draw all forces acting at the center of mass, even though friction and normal reaction force act at the point of contact with the surface. Please use a ruler, and do it in pencil so you can correct mistakes. Label forces using the following symbols: w = weight of rock, T= tension, n = normal reaction force,/= friction.

 


  

 

 


 

 

 

 

 

 

 

 

 

 

 


 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 


 

 

 

 


 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Activity:  Graphing Motion

  • Groups of 3 or 4

  • Match graph (Position vs Time)

  • Print results (just one from your team) & turn in.