Monday 8 Nov:

 

Journal Q's

 

 

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What is happening to the A) Velocity and B) Acceleration  for each graph?

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Answers: A) 

I: Velocity is constant (+)

II: Velocity is zero but it is also constant

III: Velocity is not constant, it is increasing (acceleration)

 

B)

I: Acceleration is zero (constant velocity), but it is also constant

II: Acceleration is zero (constant velocity), but it is also constant

III: Acceleration is not zero (changing velocity), since velocity is increasing, there is + acceleration

 

 

 

 

 

 

2.The cart of mass 10 kg shown above moves without frictional loss on a level table. A 10 N force pulls on the cart horizontally to the right. At the same time, a 30 N force at an angle of 60° above the horizontal pulls on the cart to the left. What is the magnitude of the horizontal acceleration of the cart?

 

 

 

 

 

 

 

 

 

 

 

 

Answers:

Fnet = ma  -->   (cos600)(30N) - 10N = (10kg)a

                         15N -10N  = (10kg)a

                            a = 5/10 --> -0.5 m/s2    

 

 

 

 

 

3. A truck exerts an average force of 2 X 107 N while pulling a trailer from rest a distance of 30 m (no acceleration, i.e., constant velocity).  This event took 10 mins.

How much work  & power did it do during this event?

 

 

 

 

 

 

 

 

 

 

 

 

W = (F)(d) --> (2 X 107 N)(30km) = 6 X 108 J

P =work/time --> 6 X 108 J / 600s  --> 1 X 106 W

 

 

4. An object (10kg) is lifted up 17.3m.

a) How much work was done?

b. What is the power used if it took 20 seconds?

 

 

 

 

 

 

 

 

 

 

 

 

 

 

a) Work = the force (direction of) used to move an

    object through a distance.

    Work = Force times distance 

      W =  (F)(d)  --> mgh = (10kg)(10N/kg)(17.3m)

       W   =  1,730 J

 

 

b) P = work/time --> (F)(d)/t -->

         1,730 J /20  --> 86.6W

 

 

 

 

 

5.

  1. A 50.0 kg mass is suspended by two ropes (500). Find  T1  & T2

                                               

                                          T1             T2                                                                                                                           

           

 

 

 

 

 

 

 

 

Sin 500 T2 = 500N

T2 = 500N/.766  = 653N

 

T1 =  Cos 500 T2

 

T1 =  .643(653) = 420N

 

 

 

 

 

 

 

 

 

6. A 25-kg object has an acceleration of -2.0 m/s2 downwards,

determine the force (Normal Force) that caused this acceleration.

                                                                                                                          

 

 

 

 

 

 

 

 

Fnet = ma  -->   (25-kg)(2N/kg)  = 50N

 

 

W = 250 and acceleration is down,

so weight is greater than the Normal force by 50N

Normal Force (N) = 200N

 

 

 

 

 

 

image006.gif

 

7. What is the velocity at various points?

 

 

 

 

 

torque

 

t = d * F┴  

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Test 9, 12, 13, 15, 16, 17  Tuesday 9 Nov 

 

 

L# 19: 1- 4, 6-15   Due Wed 10 Nov (Constant Acc)

L# 20: 1- 5, 7, 9 - 16   Due Friday 12 Nov (Specific Heat)

L# 21: 1,2, 4 - 6, 9-16   Due Mon 15 Nov (Momentum)

L# 22: 1- 5, 7- 9, 12, 14 - 20   Due Wed 17 Nov

(Calculus: Derivative & Integration )

L# 23: 1-4, 8, 13, 15, 16, 18, 20   Due Fri 19 Nov

(Center of Mass)

 

Review Monday 22 Nov

Test  L# 19 - 23  Tues 23 Nov

 

 

 

 

 

 

 

 

. Bridge Contest:

  • Due by Friday Dec 17

 

 

 

 

Tower Contest:

  • Due by Friday Jan 7th