Transcript 1D Kinematics

Ch1: 1D Kinematics
1. Preview of concepts
2. Recall main points: position, displacement, velocity
and acceleration (geometrically and algebraically)
3. Discuss Pre-lecture and Check Points
4. Examples of problems
1. Preview
Position x of point P in 1D: Axis, Origin, Direction
Position, velocity, acceleration
v
1. Preview
Graphs x vs t, v vs t
2 Main Points
Algebraic relationship from x to v to a.
Start with x(t)=2t-1
2. Main Points
Special case: Motion with constant a: from a to x
Graphical x, v, a
Algebraic x, v, a
3 Discuss
Checkpoint 1:For the Displacement and Velocity
curves shown on the left, which is the correct plot of
acceleration vs. time?
A
B
1.2 Discuss
CheckPoint 2:
At t = 0 a ball, initially at rest, starts to roll
down a ramp with constant acceleration.
Suppose it moves 1 foot between
t = 0 sec and t = 1 sec.
How far does it move between t = 1 sec and t
= 2 sec?
Set up problem (always same way ):
1. Picture: Axes with origin and direction
2. Equations relevant to problem and specified for axis choice
3. Constraint Equations
4. Solution
4. problems
Previous page cont’d
4. problems
Relative signs of x, v, a and relation to speed and
slowing down or speeding up. Difference between the
quantity and its magnitude.
Given the axes we chose, and the origin we chose, is the quantity describing the
motion (position or velocity or acceleration)
A. A positive number
B. A negative number
C. Zero
D. Not enough info is given to determine the number
Example. Throw object up in the air.
a. How high does it go above release point, given vo?
4. problems
1.
2.
3.
4.
Picture with axes and origin
Generic equations relevant for the problem
Constraint equation
Solution
Example. Throw object up in the air.
b. How long does it stay in the air, given vo?
4. problems
1.
2.
3.
4.
Picture with axes and origin
Generic equations relevant for the problem
Constraint equation
Solution
4. problems
Example. Two objects up in the air. Released at same time, the first from h at v1o=0, the other from y=0 with
v2o=vo At what time will they pass each other (similar to homework problem)
1.3 problems
Example.