Physics 111/121
Vector Mini-Review Problem
Solutions
Contents
FOP
FOP
FOP
FOP
3-11, 3-18, 3-15, 3-21
5-6, 5-7
7-6, 7-11
10-46, 12-19, 12-21, 12-25
1
Problem 3-11:A woman walks 250 m in the direction 30° east of north, then 175 m directly east. Find (a) the magnitude and (b) the
angle of her final displacement from the starting point. (c) Find the distance she walks. (d) Which is greater, that distance or the
magnitude of her displacement?
2
Problem 3-18: Here are two vectors:
What are (a) the magnitude and (b) the angle (relative to i ) of a? What are (c) the magnitude and (d) the angle of b ? What are
(e) the magnitude and (f) the angle of a + b ; (g) the magnitude and (h) the angle of b - a ; and (i) the magnitude and (j) the
angle of a - b ? (k) What is the angle between the directions of b - a and a - b ?
3
Problem 3-18, continued
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5
6
Problem 5-6: Three astronauts, propelled by jet backpacks, push and guide a 120 kg asteroid toward a processing dock, exerting the forces
shown in the figure. What is the asteroid's acceleration (a) in unit-vector notation and as (b) a magnitude and (c) a direction?
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8
Problem 7-6 A floating ice block is pushed through a displacement d = (15 m)i - (12 m)j along a
straight embankment by rushing water, which exerts a force F = (210 N)i - (150 N)j on the block. How
much work does the force do on the block during the displacement?
9
Prob 7-11: The figure shows
three forces applied to a trunk
that moves leftward by 3.00 m
over a frictionless floor. The force
magnitudes are F1 = 5.00 N, F2 =
9.00 N, and F3 = 3.00 N. During
the displacement, (a) what is the
net work done on the trunk by the
three forces and (b) does the
kinetic energy of the trunk
increase or decrease? By how
much?
10
Problem 10-46: Two 2.0 kg bodies, A and B, collide. The velocities before the collision VA = 15i + 30j and vB = -10i + 5.0j.
After the collision, v´A = -5.0i + 20j. All speeds are given in meters per second. (a) What is the final velocity of B? (b) How
much kinetic energy is gained or lost in the collision?
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