Learning Goal:

To learn to use images of an object in motion to determine position, velocity, and acceleration.

### PROBLEM

### Two toy rockets are traveling in the same direction (taken to be the *x-axis*). A diagram is shown of a time-exposure image where a stroboscope has illuminated the rockets at the uniform time intervals indicated. (Figure 1)

### A) At what time(s) do the rockets have the same velocity?

### B) At what time(s) do the rockets have the same x position?

### C) At what time(s) do the two rockets have the same acceleration?

### D) The motion of the rocket labeled A is an example of motion with uniform (i.e., constant) __________.

### E) The motion of the rocket labeled B is an example of motion with uniform (i.e., constant) __________.

### F) At what time(s) is rocket A ahead of rocket B?

**Answers:**

**Part A)**

at some instant in time between t=1 and t=4

**Part B)**

at times t=1 and t=4

**Part C) **

at no time shown in the figure

**Part D)**

and nonzero acceleration

**Part E) **

velocity

**Part F)**

before t=1 and after t=4