Transcript Slide 1

Physics 218: Mechanics
Instructor: Dr. Tatiana Erukhimova
Lecture 10
A faulty model rocket moves in the xy-plane (the positive ydirection 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 v0  v0 x i  v0 y j with v0 x  1.00 m / s and v0 y  7.00 m / s.
a) Calculate the velocity and position vectors as functions of time.
b) What is the maximum height reached by the rocket?
c) What is the horizontal displacement of the rocket when it
returns to y=0?
A physics professor did daredevil stunts in his spare
time. His last stunt was an attempt to jump across a
river on a motorcycle. The takeoff ramp was inclined
at 53.00, the river was 40.0 m wide, and the far bank
was 15.0 m lower than the top of the ramp. The river
itself was 100 m below the ramp. You can ignore air
resistance. a) What should his speed have been at the
top of the ramp to have just made it to the edge of the
far bank? b) If his speed was only half the value
found in (a), where did he land?
An object is at the point x = L and y = H at the time t=0. It
has velocity given by



3
v (t )  c1ti  c2t j
where c1 and c2 are constants. Find the position and
acceleration as functions of time.
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
Have a great day!
Reading: Chapter 5,6
Hw: Chapter 6 problems and
exercises