Bell Ringer1. If the velocity of a particle is nonzero, can

the particle’s acceleration be zero? Explain

2. If the velocity of a particle is zero, can the particle’s acceleration be zero? Explain

3. If a car is traveling eastward, can its acceleration be westward? Explain

4. If the average velocity of an object is zero in some time interval, what can you say about the displacement

of the object during that interval?

Practice Problem 1

A car is traveling due east at 25.0 m/s at some instant.

a) If its constant acceleration is 0.750 m/s^2 due east, find its velocity after 8.50 s have elapsed.

b) If its constant acceleration is 0.750 m/s^2 due west, find its velocity after 8.50 s have elapsed.

Practice Problem 2

A car traveling east at 40.0 m/s passes a trooper hiding at the roadside. The driver uniformly reduces his speed to 25.0 m/s in 3.50 s.

a) What is the magnitude and direction of the car’s acceleration as it slows down?

b) How far does the car travel in the 3.5 s period?

Practice problem 3 (Involving 2 objects)

A car traveling at a constant speed at 24.0 m/s passes a trooper hidden behind a billboard

One second after the speeding car passes the billboard, the tropper sets off in chase with a constant acceleration of 3.00 m/s^2.

a) How long does it take the trooper to overtake the speeding car?b) How fast is the trooper going at that time?

Practice Problem 4 (Involving two objects)

A motorist with an expired license tag is traveling at 10.0 m/s down a street

And a policeman, taking another 5.00 s to finish his donut, gives chase at an acceleration of 2.00 m/s^2.

Find a) The time required to catch the carb) The distance the trooper travels while

overtaking the motorist

Practice Problem 5 (Involving horizontal motion with two phases)

A typical jetliner lands at a speed of 160 mi/h and decelerates at the rate of (10 mi/h)/s.

If the plane travels at a constant speed of 160 mi/h for 1.0 s after landing before applying the brakes…

…What is the total displacement of the aircraft between touchdown on the runway and coming to rest?

A jet lands at 80.0 m/s, the pilot applying the brakes 2.00 s after landing. Find the acceleration needed to stop the jet within 5.00 x 10^2 m.

Practice Problem 5 (Involving horizontal motion with two phases)