2.3 Time, Velocity, and Speed

This covers the title's content and is based for UWaterloo's Physics 111 program. The dots with two on top and one on the bottom mean since and the opposite is therefore.

Time

the interval over which change occurs

What is the SI (Standardized Unit) for physics?

seconds (s)

How can you represent elapsed time mathematically?

∆t = t_f - t₀

What does a large displacement tell you about your velocity?

you have a high velocity

What is the Derived Unit for Velocity?

m/s or m s⁻¹

What is average velocity’s symbol? What is its equation?

v (with bar on top) = average velocity

∆x = change in displacement

∆t = change in time

₀ = initial

_f = final

Why does constant acceleration use average velocity and not instantaneous velocity?

• if acceleration is constant and ≠ 0, then eventually, velocity changes

• instant velocity cannot represent this ∵ ∆t is too small

Is velocity a vector or not? Why or why not?

∵ displacement is a vector

∴ velocity is a vector

Does the sign of the displacement (x) affect the sign of velocity (v)? If it does, how does it affect it?

1. it does affect velocity’s sign

2. the change in displacement’s sign, determines the velocity’s sign

   1. ex. if the displacement is negative, then velocity is negative

Given velocity and acceleration, how can you find time?

v_avg/a = ∆t