Forces in Two Dimensions
Practice Test
1.
A sled of mass 40.0 kg is pulled along flat, snow-covered ground. The static friction coefficient is 0.28, and the kinetic friction coefficient is 0.08. What force will be needed to start the sled moving?
a.
110 N
b.
31 N
c.
392 N
d.
147 N
Hint
2.
To find the magnitude of the resultant vector for two vectors that are at some angle other than 90°, use __________.
a.
the Law of Cosines
b.
R
2
=
A
2
+
B
2
c.
the Pythagorean theorem
d.
R
2
=
A
2
-
B
2
Hint
3.
A 475-N trunk is resting on a plane inclined 40.0° above the horizontal. Find the components of the weight force parallel and perpendicular to the plane.
a.
F
g
x
= -364 N,
F
g
y
= -305 N
b.
F
g
x
= -305 N,
F
g
y
= -364 N
c.
F
g
x
= 305 N,
F
g
y
= 364 N
d.
F
g
x
= 364 N,
F
g
y
= 305 N
Hint
4.
A(n) __________ is a vector that is equal to the sum of two or more vectors.
a.
graphical representation
b.
resultant
c.
addition vector
d.
displacement
Hint
5.
Two ropes pull on a ring. One exerts a 50.0-N force at 42.0°, the other a 87.0-N force at 70.0°. What is the net force on the ring?
a.
100 N at 56.0°
b.
133 N at 30.0°
c.
100 N at 60.0°
d.
133 N at 60.0°
Hint
6.
When there is no relative motion between two surfaces, the force exerted by one surface on the other is called __________.
a.
the static friction force
b.
kinetic friction
c.
the kinetic force
d.
resistance
Hint
