Kinematic Review
Test Topics:
● 1D motion, speed vs. velocity, distance vs. displacement, vector and scaler.
● Uniform motion vs. Non-Uniform Motion
● Graphs of Motion (d-t, v-t, a-t)
● Acceleration, Famous Five
● Acceleration Due to Gravity
● 2D motion
● Projectile Motion
Terminology
Scaler: quantity with NO DIRECTION (25s, 60kg)
Vector: quantity with DIRECTION (10m [North])
Distance: TOTAL LENGTH of path taken
Displacement: “Shortest Path” from start point to end point
Position: distance and direction form a reference point
Speed: rate of change in distance (how fast something is travelling)
Velocity: rate of change in displacement (how fast something is travelling, IN SPECIFIC DIS.)
Acceleration: rate of change in velocity
Uniform Motion:
Uniform Acceleration:
Avg. Speed and Velocity
Speed:
Velocity:
Total distance / Time
Displacement / Time
1D motion
Finding Resultant Displacement:
1) ▵ d = d2 - d1
2) ▵ d = d1 + d2 + d2 …
When to use:
1) When finding from a POSITION
Directions:
One direction will be positive, the other will
be negative.
2) Multiple movements
Ex:
[N] = +
[S] = -
2D motion
1. Find the displacement (hypotenuse) using pythagorean theorem
a. From start point to end point after drawing a diagram of the distance travelled.
▵ d = √a2 + b2
2. Find angle from STARTING POINT using Tan
a. θ= tan-1 (opp/adj)
3. Using displacement and angle, write the direction
a. Ex.
___ km [ _ S of E]
→ to find the speed and/or velocity from 2D (or 1D) use formulas above.
Graphing
Uniform Motion
PT Graph:
Straight Diagonal Lines - No Curves
VT Graph:
Straight Horizontal Lines
→ to calculate velocity:
Find slope for each line segment (rise/run)
→ to calculate displacement (P):
Find area under each line (bxh)
● The velocity is CONSTANT
● Positive slope = forwards (positive direction)
● Negative slope = backwards (negative direction)
○ Line going under x-axis = object going past origin
Non-Uniform Motion
PT Graph:
A curve
→ to calculate velocity:
Use TANGENT LINE and
find slope of that line
(rise/run)
- Plot the slope value at
given time value
VT Graph:
Straight Diagonal Lines - No
Curves
AT Graph:
Straight Horizontal Lines
→ to calculate displacement:
FInd area under each line
( bxh or bxh/2 )
→ to calculate velocity:
Find area under each line
(bxh)
→ to calculate acceleration:
Find slope of each line
(rise/run)
● To find resultant displacement
○ Add up all the displacement values (the areas)
PT Graph:
VT Graph:
Going Upwards (Steeper):
- Forward (+) direction
- Increasing in speed
Upward Diagonal Line:
- Positive
Going Upwards (Not Steep):
- Forward (+) direction
- Slowing in speed
Downward Diagonal Line:
- Negative
Going Downwards (Steeper):
- Backward (-) direction
- Increasing in speed
Going Downwards (Not Steep):
- Backward (-) direction
- Slowing in speed
Acceleration (Famous 5)
→ using your given and unknowns, find the correct famous 5 formula and solve for what
needs to be found.
Directions should be + and -
Acceleration with Gravity
→ same concept, only difference: acceleration will always be 9.8 m/s2 [down]
→
- 9.6 m/s2
Projectile Motion
1. Figure out the horizontal (X) and vertical (Y) values.
a. Y’s acceleration will always be 9.80
b. Y’s initial velocity will always be 0
2. Once you have all the values: use the famous 5 formulas to find what needs to be found
a. HORIZONTAL HAS ITS OWN FORMULA
3. To find FINAL VELOCITY
a. Make a “triangle” from where the ball is launched
b. Find the missing side value by isolating V2 from famous 5 equation
i.
Ex.
Vy2 = Vy1 + aT
ii. THIS WILL ALLOW YOU TO HAVE VERTICAL VELOCITY AND
HORIZONTAL VELOCITY
c. Then find the angle from starting point
i.
Use pythagorean theorem
ii. Then use Tan -1
ALWAYS USE GUESS METHOD