Download Assume circular orbits

EXAM #1
PHYS 2053 SEC 0001
Name
FALL 2007
PID
MULTIPLE CHOICES (40 pts): Choose the one alternative that best completes the
statements or answers the question.
(5 pts) 1.) The distance from an adult's elbow to her fingertips is closest to
A) 5 cm
B) 10 cm
C) 50 cm
D) 1 m

(5 pts) 2.) If vector A has components Ax = -2.00 and A y = 3.00, then the magnitude of

A is;
A) 13
B) 1
C) 13
D) - 13
(5 pts) 3.)
+y
A
+x
Which answer applies to the components of vector A (the signs of Ax and Ay)?
A) (+x, +y)
B) (+x, -y)
C) (-x, +y)
D) (-x, -y)
(5 pts) 4.)
What is the average velocity between positions D and E?
A) 5 m/s
B) -5m/s
C) 30 m/s
1
D) -30 m/s
(5 pts) 5.)
Is the average acceleration between time 2 second and time 3 second is the same as?
A) Between 0 s and 4 s B) Between 6 s and 7 s
C) Between 1 s to 7 s D) All A, B, C
(5 pts) 6.)
B
C
A
A ball is kicked from point A, neglect the air resistance, what happens to the horizontal
velocity of the ball between the points B and C?
A) increased
B) decreased
C) stay the same
D) doubled
(5 pts) 7.)
An athlete runs on the circle, as shown in the figure, with constant speed of 7 m/s. What
is the velocity at point D?
A) (-7 m/s, 0)
B) (-7 m/s, -7m/s)
C) (0, -7m/s)
(5 pts) 8.)
A worker pulls horizontally on a crate on a rough horizontal floor,
causing it to move forward with constant velocity. In the figure,
force A is the pull of the worker and force B is the force of friction
due to the floor. Which one of the following statements about these
forces is correct?
A) A > B B) A < B
2
C) A = B
D) (0, 0)
Problem #1 (10 pts). Assume circular orbits (consult the equations sheet).
a) What is the magnitude of the orbital velocity, in m/s, of the Neptune around
the sun? (5 pts)
b) What is the radial acceleration, in m/s2, of the Neptune toward the sun? (5 pts)
Problem #2 (30 pts). A man stands on the roof of a 48.0 m-tall building and throws a
rock with a velocity of magnitude 21.0 m/s at an angle of 37.0o above the horizontal. You
can ignore air resistance.
a) Calculate the maximum height above the roof reached by the rock.(10 pts)
b) Calculate the magnitude of the velocity of the rock just before it strikes the
ground. (10 pts)
c) Calculate the horizontal distance from the base of the building to the point
where the rock strikes the ground. (10 pts)
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Problem #3 (20 pts). A 1.5 kg picture is suspended by two cables, as shown in the
figure below.
45o
45o
a) Draw a free body diagram of the picture (5 pts)
b) Write the equilibrium condition (sum of the forces) for the x-direction
(horizontal). (5 pts)
c) Write the equilibrium condition (sum of the forces) for the y-direction (vertical).
(5 pts)
d) Calculate the tension on each cable (5pts)
4