Average/Instantaneous Acceleration

Physics 513

Let’s Apply What We’ve Learned Together…

• A car traveling West in a straight line on a highway decreases its speed from 30.0 meters per second to 23.0 meters per second in 2.00 seconds. The car’s average acceleration during this time interval is

Now Image the Problem as Follows…

• As a car is driven West in a straight line with a positive acceleration the car must be

 • (1) speeding up• (2) slowing down• (3) travelling at a constant velocity• (4) standing still• (5) impossible to determine

Let’s Talk about This One…

• If the velocity of a particle is nonzero, can its acceleration be zero? Explain

Constant Acceleration

Physics 513

Let’s Exercise Those New Equations

• A motorcyclist heading east through a small town accelerates at a constant 4.0 m/s2 after he leaves the city limits. At time t = 0 he is

5.0 m east of the city-limits signpost, moving east at 15 m/s.

(a)Find his position and velocity at t = 2.0 s. (b)Where is he when his velocity is 25 m/s?

This One is Trickier

• A car traveling at a constant speed of 45.0 m/s passes a trooper hidden behind a billboard. One second after the speeding car passes the billboard, the trooper sets out from the billboard to catch it, accelerating at a constant rate of 3.00 m/s^2. How long does it take her to overtake the car?

Please Consider This…

• Can the equations of kinematics be used when the acceleration is zero?