Ch. 11 Sec. 3Acceleration

Rate of change in velocity.

Really a description of “how fast you can go in a certain amount of time”.

Good acceleration is being “quick to change”.

AccelerationAcceleration

Change in Speed

Push or pull feeling Acceleration by increasing speed or decreasing in

speed (negative acceleration) Acc. = final velocity – original

velocity time

Units: m/sec/sec

Change in Direction Turning a curve changes acceleration even at

constant speed Constant Acceleration

Steady change in velocity in a straight line

A car increases its speed from 60 km/hr to 80 km/hr in 4 seconds. What is the car’s acceleration?

Acceleration ProblemAcceleration Problem

80 km/hr – 60 km/hr

4 sec.

1st second – 65 km/hr

2nd second – 70 km/hr

3rd second – 75 km/hr

4th second – 80 km/hr

5 km/hr/sec.

Acc = Δ velocity

time

Acceleration problem An airplane reduces its speed from 250 km/hr

to 175 km/hr in order to come into the run way. What was the negative acceleration of the plane?

Speed-Time Graph Slope of the speed time graph is acceleration

Distance-Time Graph Nonlinear graph

showing accelerated motion

Curve motion

Instantaneous Acceleration How fast velocity is changing at a specific

instant Involve change in velocity or direction Always changing

Acceleration problem A runners acceleration is 5.5 m/s/s. If the

runner first starts at 0.0 m/s and has a final velocity of 21.0 m/s. How long will it take?

Rates of Motion TableRates of Motion Table

Rates Definition Equation Unit Graph

Speed

Velocity

Acceleration