Mini Quiz: In PEN w/ no cross outs!
1) At what position is the vertical velocity zero?
2) What is the direction of the acceleration of the rock at point B?a) Upwardb) Downwardc) In the direction of point Cd) In the direction of point A
Mini Quiz: In PEN w/ no cross outs!
A stone is thrown horizontally from the top of a 25.00-m tall cliff. If the stone has a horizontal velocity of 15m/s, how far horizontally from the edge of the cliff will the stone land?
5) What is the first thing you need to calculate to solve this problem?a) Horizontal velocityb) Vertical velocityc) Drop timed) Height of the cliff
3) For an object that is accelerating, the velocity vs. time graph has what type of “shape”
a) Sloped Lineb) Curve c) Flat lined) I don’t know
4) For an object that is accelerating, the position vs time graph has what type of “shape”
a) Sloped Lineb) Curve c) Flat lined) I don’t know
Mini Quiz: In PEN w/ no cross outs!
6) Which of the following v vs. t graphs shows an object moving to rest?
7) Jordon runs at 30m/s. Alicia bikes at 60m/s. If they both travel for 5 seconds, then Alicia will travel:
a)Twice as farb) The same distancec) Four times as fard) Half as far
Av
m/s
(s)0
vm/s
(s)0
vm/s
(s)0
vm/s
(s)0
B C D
Mini Quiz: In PEN w/ no cross outs!
8) Which interval is the object not moving?9) Which interval is the object accelerating?10) Which interval is the object moving backward?a)I -IIb) II-IIIc) III-IVd) IV-V
Mini Quiz: In PEN w/ no cross outs!
11) Which correctly shows the resultant vector of the following two velocities:
a) b) c) d) Zero
12) What is the x component of the following vector:
a) 8.66 b) 51.96N
c) 5.0N d) 29.54N30°
60°
10N
Mini Quiz: In PEN w/ no cross outs!
13) What is the y component of the applied force?
a) 17.2N b) 21.7N
c) 25N d) 12.5N
14) What is the x component of the following vector:
a) 5.0N b) 9.6N
c) 13.0N d) 28.9N
30°
30°
25N
15N
Announcements
Hello Lexa and Johnny (and any other student viewing this). Use this powerpoint to catch up on what you missed!
Forces Introduction
•New Sheet: Lets look at what we know so far…..
•Go through side 1 together•(This is the Forces_Notes 4)…also posted
on my Wiki
Forces WHITEBOARDSFor each of the following questions, determine the net force. You must SHOW YOUR WORK for each question
Y
NET FORCE Vector
X
For the following slides:•1) Find the NET FORCE▫This means you find the sum of the forces acting on
the object. Watch out for the direction. Left = (-) and right = (+). Up = (+), down = (-)
The following diagrams have forces at an ANGLE
•Forces at an angle have x and y components
•X component = Fcos(θ)•Y component = Fsin(θ)
•Example:•X = 25cos(30)•Y = 25sin(30)
30
25N
Forces IntroductionBut Physics is not just imaginary forces with arrows.....
Often force problems involve real objects, with actual forces acting on them.
We use FREE BODY DIAGRAMS to show these forces
Forces Introduction
WWeight (Gravity): Always directly downward. W = mg
m = mass g = gravity
FN
Normal: A surface pushes perpendicular against an object.
FN is Equal and Opposite of
the sum of all downward forces
Ff
Friction: A force that prevents/goes against (dampens) motion
Will change depending on the surface.
FT
Tension: A PULL in the direction of a rope or a wire
Pulled Object: Value will be given
Hanging: FT is Equal and
Opposite of the sum of all downward forces
FApplied Force: A force can be a push or pull applied to an object
Fx = Fcos( )θ
Fy = Fsin( )θ
* = Angle from the horizontal*θ
Forces IntroductionHow to Solve Equilibrium Problems:
1) Add up the X forces (including x components)
2) Add up the Y forces (including y components)
3) Find the RESULTANT VECTOR.
Forces IntroductionA man pulls a 300kg box at CONSTANT VELOCITY across the floor. He applies a 600N force at an angle of 30°. What is the FRICTION FORCE? Include a magnitude and
direction (left or right).
Free Body: