Topic 5 - 1D Motion: Kinematics Equations [Constant Acceleration]

Question 1

What can we analyze with 1D kinematics?

Answer 1

• Motion along a straight line —> assume constant acceleration
• Need to define the starting point, and the finish/end point —> must draw a diagram
• Need to define a frame of reference (ie. which direction is positive) from start to finish —> label diagram
• Can then analyze displacement, velocity and
  acceleration —> create equations to relate quantities

Question 2

Constant Acceleration

Answer 2

When an object moves with constant acceleration, the instantaneous acceleration at any point in time is equal to the average acceleration over the entire time interval
𝑡 (it’s constant!)

• We now write acceleration as just 𝑎

Question 3

The big 5 Kinematics Equations

Answer 3

Question 4

Free Fall

• Note that 𝑔 (gravity) is a scalar (magnitude only)
• If we want to describe vector acceleration, we can use
  𝑎 = −𝑔 if the acceleration is downwards

Answer 4

When an object is falling under the influence of gravity alone

𝒈= 𝟗.𝟖1m

We use a constant gravitational free-fall acceleration of

• Air resistance is negligible and initial motion is disregarded
• Frame of reference will be vertical with (usually) +𝑦 pointing up and −𝑦 pointing down

Question 5

Problem Solving Approach to 1D Kinematics

Answer 5

1. Read the question and highlight was your end goal is (what you’re trying to find)
2. Always set a frame of reference and what direction is positive
3. Draw a diagram and label all important events (initial/final values, time(s), etc.)
4. Make a list of all known/unknown variables – pick which kinematics equations to use
5. Apply the proper kinematics equations and solve for desired variable