Arizona State University| PHY 121: Univ Physics I: Mechanics|Homework 1-1| Motion of Two Rockets

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?

 

 Two toy rockets A and B are traveling in the same direction (to the right). Six positions of each rocket at six points of time are shown. For the rocket A, the distance between two nearby points increases from left to right. For the rocket B, the distance between two nearby points is constant. At the point where t equal 0 rocket A is to the right from rocket B, at t equal 1 and 4 both rockets are at the same position of the x-axis, at t equal 2 and 3 rocket A is to the left from rocket B and at t equal 5 rocket A is to the right from rocket B.
Figure 1

 

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

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