Assignment:
Average velocity is determined by dividing displacement by time. Position in a chuck wagon race can be illustrated with a vector arrow drawn from the starting point to the current location. The following diagram illustrates several position vectors drawn at different times in the race.
Use this diagram to explain why the displacement becomes zero just as the chuck wagon crosses the finish line and why the chuck wagon has an average velocity of zero when it reaches the finish line.
1. Calculate the displacement (magnitude and direction) of the ball when it is moved from the initial to the final position.
initial position (x, y)i = (-10.0, 10.0) m
final position (x, y)f = (15.0, -10.0) m
Show your work and use the simulation to verify that the answer you calculated is correct.
2. Calculate the average speed and the average velocity for a ball that is moved according to the following instructions.
Reset the simulation, and position the ball at (x, y)i = (10.0, -5.0) m.
Drag the ball along any curved path to somewhere near (x, y)f = (-20.0, -10.0) m.
a. Show the average speed calculations.
b. Show the average velocity calculations.
c. Why is the average speed always greater than the magnitude of the average velocity?
3. According to figure below, the velocity and acceleration have a negative direction.
a) Does a negative acceleration necessarily mean that something is slowing?
b) What orientation of velocity and acceleration will cause something to initially slow down?
c) What orientation of velocity and acceleration will cause something to initially speed up?
4. Set up the simulation to illustrate the motion of a baseball that is thrown straight up.
a) Above each of the following words, draw the initial velocity vector and the constant acceleration vector.
b) Is there a point on the trajectory where the ball has zero velocity? Where on the trajectory does this occur?
c) Is there a point on the trajectory where the ball has zero acceleration? Explain.
5. Based on your observations from the simulation, do you think it is possible for an object to accelerate yet neither speed up nor slow down? Explain why or why not.
6. It is clear that acceleration will change the magnitude and/or direction of the velocity. With this in mind, complete the following list of accelerators common to all vehicles.
a. Which causes an acceleration that maintains or changes the car's velocity, controlled by the gas pedal.
b. Which causes an acceleration that opposes the car's velocity, controlled by the brake pedal.
c. Which causes an acceleration that changes only the direction of the car's velocity.
7. If two Smart cars depart from the same location at the same time and travel different routes to the same final destination, arriving at the same time, prepare to explain why the following statements are true.
a) The cars have traveled different distances but have the same displacement.
b) The average velocity of each car is identical even though they traveled at different speeds.
c) When the brakes on the cars were used, the acceleration was not necessarily negative.
d) The steering wheel on each car was used to change the velocity of the car without changing the speed.