1. Chapter Three Review

2. Vectors have a direction
Displacement
Velocity
Acceleration
Force

3. Force 1
Force 2
45°
45°
What force will
balance Force 1
and Force 2?

4. All vectors in two dimensions can be broken into an x and y component
20m(sin40°)
40°
20m(cos 40°)

5. Motion in the x direction is independent of motion in the y direction

6. In a horizontally launched projectile, use the height
vx = 20 m/s
Dt = 1.43 s
Dx = vxDt
Dx = 28.6 m
Dy = 10 m
In a horizontally launched projectile, use the height
to calculate the time in the air. Use vx to calculate
how far it goes.

7. a b c d e

8. vx vy vi vx

9. x = -8m(cos25°) + 3m(cos40°) + 4m = -.95mA B
8 m
3 m C
25°
40°
4 m
Find the resultant
x = -8m(cos25°) + 3m(cos40°) + 4m =
-.95m
y = 8m(sin25°) + 3m(sin25°) =
5.31m

10. x = -.95m y = 5.31m c2 = (-.95m)2 + (5.31m)2 c = 5.39 mq
c2 = (-.95m)2 + (5.31m)2
c = 5.39 m
tanq = 5.31m / -.95m
q = -79.9°
q = 180° ° = 100.1°

11. I throw a football at an angle
of 50° with an initial velocity
of 20 m/s. How far does it
go?
Dy = vi(sinq)Dt + (1/2)g(Dt)2
= 0
Dt = -2visinq/g
= 3.12 s
Dx = vi(cosq)Dt
= 40.1 m