Monday 21 Sep:

Target: Use of motion equations  (& Quiz)

1. (Relationship between work and energy)

   W = DKE + DPE

2.     (net force – Newton’s 2^nd law)

SF = ma

3.   (Definition of acceleration- relationship with velocity)

    a = DV / t

4.      (Distance after a period of time)

     X_f = X_o+ V_ot  + ½ at²

5.     (Velocity after a period of time)

     V_f = V_o+ at 

6.     (Velocity/distance/acceleration without time)

    V_f²  = V_i²+ 2aDx 

7.     (Mechanical Work)

   W = f(x)

8.     (Force of friction)

    F_frict = m F_N

9.     (Kinetic Energy)

    KE = ½ m V²

10.     (Potential Energy)

      DU_g = mgh

11.   (Definition of Linear momentum)

        r =  mV

12.   (Definition of change of momentum and Impulse)

         Dr      =   Imp

        D(mV) =   D(f t)

Journal:

 1. A ball is shot with a velocity of 20 m/s from the ground @ 30⁰.

a. How long will it take to hit the ground?

b. What height will it reach?

c. What is the Speed when it hits the ground?

d. How far does it travel?

a.  V_f = V_o + at  

   -20m/s = 20m/s + (-10m/s²)(t)

   -40m/s / -10m/s^{2 =} t

      t = 4.0s

b. X_y = V_ot + ½ at² 

X_y  =  (20m/s) (2.0s) + (.5)(-10)(2)²

X_y  =  20m

2. A ball is shot to a height of 100m from the ground.

a. What was the initial velocity?

b. How long did it take to reach the apex?

a. V_f² – V_o² = 2aDX

    0 – V_o²  = 2(-10m/s²)(100m)

     V_o =  -(-2000)^-2   --> 44.7m/s

b. V_f = V_o + at  

   0 = 44.7m/s  + (-10m/s²)(t)

      t = 4.47s

Correct Pre-Test