Transcript C) 1.84 x 10 5 Pa

Chapter 9
Pretest
Fluids
1. Because a buoyant force acts in the
opposite direction of gravity,
A) objects submerged in water have a
net force smaller than their weight.
B) objects submerged in water have a
net force larger than their weight.
C) objects submerged in water have a
net force equal than their weight.
D) objects submerged in water appear
to weigh more than they do in air.
1. Because a buoyant force acts in the
opposite direction of gravity,
A) objects submerged in water have
a net force smaller than their weight.
B) objects submerged in water have a
net force larger than their weight.
C) objects submerged in water have a
net force equal than their weight.
D) objects submerged in water appear
to weigh more than they do in air.
2. The flow rate of blood
through the average human
aorta is about 9.0 X 101
3
cm /s. If the aorta has a
radius of 1.0 cm, what is the
velocity of the blood flow?
A) 14 cm/s,
B) 32 cm/s,
C) 37 cm/s,
D) 29 cm/s
2. The flow rate of blood
through the average human
aorta is about 9.0 X 101
3
cm /s. If the aorta has a
radius of 1.0 cm, what is the
velocity of the blood flow?
A) 14 cm/s,
B) 32 cm/s,
C) 37 cm/s,
D) 29 cm/s
3. Two paper cups are hung by
strings 10 cm apart. If a person
blows between the cups,
A) they move toward each other,
B) they move away from each
other,
C) they do not move,
D) they move upward.
3. Two paper cups are hung by
strings 10 cm apart. If a person
blows between the cups,
A) they move toward each
other,
B) they move away from each
other,
C) they do not move,
D) they move upward.
4. At a constant volume, an ideal
gas is heated from 348 K to 423 K.
If the original pressure in the tank
was 1.51 x 105 Pa and the volume
does not change, what is the new
pressure?
A) 1.24 x 105 Pa
B) 9.75 x 104 Pa
C) 1.84 x 105 Pa
D) 4.97 x 102 Pa
4. At a constant volume, an ideal
gas is heated from 348 K to 423 K.
If the original pressure in the tank
was 1.51 x 105 Pa and the volume
does not change, what is the new
pressure?
A) 1.24 x 105 Pa
B) 9.75 x 104 Pa
C) 1.84 x 105 Pa
D) 4.97 x 102 Pa
1. What is the
difference in a
fluid and a
liquid?
A fluid is liquids and
gases. Particles
can flow around
each other.
2. What
determines
whether an object
will sink or float?
If the density is lower
than the fluid’s density.
If the buoyant force is
equal to the weight.
3. What is the
pressure at a
depth of 650 m
in a lake?
P2 = P1 + rgh
P2 =
5
10
+ 1000(10)650
P2 = 6600000 Pa
4. (A) Water flows through a hose
with a diameter of 0.20 cm at a
speed of 3.0 m/s. If you put your
thumb over the end of the hose and
produce an effective diameter of
0.10 cm, at what speed does the
water exit the hose? (B) If the
pressure at the faucet is 3 x 105 Pa,
what is the pressure at the thumbcovered end of the hose?
Av = Av
2
2
p(0.1 ) x 3 = p(0.05 ) x v
v = 12 m/s
2
P1 + 1/2 ρv1 + ρgh1 =
2
P2 + 1/2 ρv2 + ρgh2
3 x 105 + 1/2 (1000)32 =
2
P2 + 1/2 (1000)12
P2 = 232500 Pa
5. My mass is 80 kg. If the
total surface area of my feet
2
is 0.08 m , what is the
pressure exerted by my feet
on the floor? If I lift one foot,
how does my weight change?
If I lift one foot how does the
pressure change?
P = F/A
P = 80 x 10 / 0.08
10000 Pa
No change in weight,
but the pressure is
doubled (half the area).