1. Instructor: Dr. Tatiana Erukhimova
Physics 218: Mechanics
Instructor: Dr. Tatiana Erukhimova
Sections 818, 819, 820, 821
Lecture 10

2. A faulty model rocket moves in the xy-plane (the positive y-direction is vertically upward). The rocket’s acceleration has components ax(t)=t2 and ay(t)=-t, where =2.50 m/s4, =9.00 m/s2, and =1.40 m/s3. At t=0 the rocket is at the origin and has velocity with and
Calculate the velocity and position vectors as functions of time.
What is the maximum height reached by the rocket?
What is the horizontal displacement of the rocket when it returns to y=0?

5. First exam Tuesday, September 18
100 HELD
7 pm

6. No calculators and cell phones
BRING YOUR STUDENT ID!
No calculators and cell phones
All liquids, gels and aerosols must be in three-ounce or smaller containers.

7. What is included?
Chapters 1-4
Kinematics, vectors

10. Kinematics

11. In components:

12. If is given, you can find and

13. Vectors

14. Friendly advice
DO NOT…

15. DO NOT use Const acceleration case formulas when acceleration is a function of time. You have to integrate or differentiate! What are the Const acceleration case formulas?

16. DO NOT write the vector sign over a projection!

17. Do Not Forget to
Write down what is given and express the answer in terms of what is given
Box the answer
Indicate the origin and positive x and y

18. Dynamics Connection between force and motion
The concept of force gives us a quantitative description of the interaction between two bodies or between a body and its environment

19. Newton’s Laws
1st Law: A body acted on by no net force moves with constant velocity (which may be zero) and zero acceleration
2nd Law: The acceleration of an object is directly proportional to the net force acting on it and is inversely proportional to its mass. The direction of the acceleration is in the direction of the net force acting on the object.
3rd Law: For every action there is an equal, but opposite reaction

20. Have a great day! Reading: Chapter 5,6
Hw: Chapter 6 problems and exercises