IV. Motion Equations for Problem Solving

 

 

When an object is moving at a constant acceleration we can use the following equations to find motion information

 

 

 

 

A. Equations (see Reference Table)

 

 

1. Average Velocity:

 

 

V = (Vi + Vf)/2

 

 

 

 

 

2. Acceleration:

 

 

a = (Vf - Vi)/t

 

 

Cross multiply & Solve 

 

 

Vf = Vi + at

 

 

 

 

3. Displacement:

 

 

V = Δd/Δt

 

 

 

 

B. Equations equations above

 

 

Take Equation 3 and solve for d

 

 

 

Δd = V Δt

 

 

 

 

• Substitute Equation 1 into previous equation

 

 

Δd =[(Vi + Vf)/2]Δt 

 

 

 

Since Vf = Vi + at

 

 

 

Δd =[(Vi + (Vi + at)/2]Δt
 

 

 

Gather like terms and solve for d

 

 

 
 

Δd =Vit +1/2at2