In Sample Prob. 5.01, for PART C, If another force, F4 = 3.0 N directed at angle 40 %3D degrees above the horizontal acts on the puck in addition to the F2 and F3, What is the acceleration of the puck?

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In Sample Prob. 5.01, for PART C, If another
force, F4 = 3.0 N directed at angle 40
%3D
degrees above the horizontal acts on the
puck in addition to the F2 and F3, What is
the acceleration of the puck?
a. -5.7 m/s^2
b. 5.7 m/s^2
c. -5.8 m/s^2
d. 5.8 m/s^2
e. -17.2 m/s^2
f.
17.2 m/s^2
g. -6.0 m/s^2
h. 6.0 m/s^2
Transcribed Image Text:In Sample Prob. 5.01, for PART C, If another force, F4 = 3.0 N directed at angle 40 %3D degrees above the horizontal acts on the puck in addition to the F2 and F3, What is the acceleration of the puck? a. -5.7 m/s^2 b. 5.7 m/s^2 c. -5.8 m/s^2 d. 5.8 m/s^2 e. -17.2 m/s^2 f. 17.2 m/s^2 g. -6.0 m/s^2 h. 6.0 m/s^2
86
CHAPTER 5 FORCE AND MOTION-I
Sample Problem 5,01 One- and two-dimensional forces, puCk
The horizontal force
causes a horizontal
acceleration.
Here are examples of how to use Newton's second law for a
puck when one or two forces act on it. Parts A, B, and C of
Fig. 5,3 show three situations in which one or two forces act
on a puck that moves over frictionless ice along an x axis, in
one-dimensional motion. The puck's mass is m- 0.20 kg.
Forces F and F, are directed along the axis and have
magnitudes F=- 4.0 N and F, - 2,0 N. Force F is directed
at angle 0= 30) and has magnitude F
ation, what is the acceleration of the puck?
This is a free-body
diagram.
(a)
Puck
1.0 N. In each situ-
(6)
KEY IDEA
B
These forces compete.
Their net force causes
a horizontal acceleration.
In each situation we can relate the acceleration a to the net
force Fet acting on the puck with Newton's second law,
F= ma. However, because the motion is along only the x
axis, we can simplify each situation by writing the second
law for x components only:
(0)
This is a free-body
diagram.
Fet,= ma,.
(5-4)
The free-body diagrams for the three situations are also
given in Fig. 5-3, with the puck represented by a dot.
(d)
C
Situation A: For Fig. 5-3b, where only one horizontal force
acts, Eq. 5-4 gives us
Only the horizontal
component of Fa
competes with Fg.
F = ma,,
which, with given data, yields
(6)
F
a, =
m
4.0 N
This is a free-body
diagram.
- 20 m/s.
(Answer)
%3D
0.20 kg
The positive answer indicates that the acceleration is in the
positive direction of the x axis.
Figure 5-3 In three situations, forces act on a puck that moves
along an x axis. Free-body diagrams are also shown.
Situation B: In Fig. 5-3d, two horizontal forces act on the
puck, F, in the positive direction of x and F, in the negative
direction. Now Eq. 5-4 gives us
dimensional.) Thus, we write Eq. 5-4 as
F - F = ma,,
F-F2 ma,.
From the figure, we see that F = F, cos 0. Solving for the
which, with given data, yields
(5-5)
acceleration and substituting for F, yield
F- F;
a, =
4.0 N 2.0 N
= 10 m/s?.
%3D
F-F F cos 0-F,
a,
0.20 kg
(Answer)
Thus, the net force accelerates the puck in the positive direc-
m
(1.0 N)(cos 30) -2.0 N
tion of the x axis.
0.20 kg
-5.7 m/s.
Situation C: In Fig. 5-3f, force F, is not directed along the
direction of the puck's acceleration; only x component F
is. (Force F, is two-dimensional but the motion is only one-
(Answer)
Thus, the net force accelerates the puck in the negative di-
rection of thex axis.
PLUS Additional examples, video, and practice available at WileyPLUS
Transcribed Image Text:86 CHAPTER 5 FORCE AND MOTION-I Sample Problem 5,01 One- and two-dimensional forces, puCk The horizontal force causes a horizontal acceleration. Here are examples of how to use Newton's second law for a puck when one or two forces act on it. Parts A, B, and C of Fig. 5,3 show three situations in which one or two forces act on a puck that moves over frictionless ice along an x axis, in one-dimensional motion. The puck's mass is m- 0.20 kg. Forces F and F, are directed along the axis and have magnitudes F=- 4.0 N and F, - 2,0 N. Force F is directed at angle 0= 30) and has magnitude F ation, what is the acceleration of the puck? This is a free-body diagram. (a) Puck 1.0 N. In each situ- (6) KEY IDEA B These forces compete. Their net force causes a horizontal acceleration. In each situation we can relate the acceleration a to the net force Fet acting on the puck with Newton's second law, F= ma. However, because the motion is along only the x axis, we can simplify each situation by writing the second law for x components only: (0) This is a free-body diagram. Fet,= ma,. (5-4) The free-body diagrams for the three situations are also given in Fig. 5-3, with the puck represented by a dot. (d) C Situation A: For Fig. 5-3b, where only one horizontal force acts, Eq. 5-4 gives us Only the horizontal component of Fa competes with Fg. F = ma,, which, with given data, yields (6) F a, = m 4.0 N This is a free-body diagram. - 20 m/s. (Answer) %3D 0.20 kg The positive answer indicates that the acceleration is in the positive direction of the x axis. Figure 5-3 In three situations, forces act on a puck that moves along an x axis. Free-body diagrams are also shown. Situation B: In Fig. 5-3d, two horizontal forces act on the puck, F, in the positive direction of x and F, in the negative direction. Now Eq. 5-4 gives us dimensional.) Thus, we write Eq. 5-4 as F - F = ma,, F-F2 ma,. From the figure, we see that F = F, cos 0. Solving for the which, with given data, yields (5-5) acceleration and substituting for F, yield F- F; a, = 4.0 N 2.0 N = 10 m/s?. %3D F-F F cos 0-F, a, 0.20 kg (Answer) Thus, the net force accelerates the puck in the positive direc- m (1.0 N)(cos 30) -2.0 N tion of the x axis. 0.20 kg -5.7 m/s. Situation C: In Fig. 5-3f, force F, is not directed along the direction of the puck's acceleration; only x component F is. (Force F, is two-dimensional but the motion is only one- (Answer) Thus, the net force accelerates the puck in the negative di- rection of thex axis. PLUS Additional examples, video, and practice available at WileyPLUS
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