Ch11_2
New Problems
reloads the page with new variable values in all questions. You must do this after grading the test to rework it another time.
Make sure to calculate your answers in SI units unless specified otherwise .
1) A wooden block with a volume of
cm
3
is held under water. What is the buoyant force on the block
(see sheet 19)
? Indicate with a positive (negative) sign whether the force you calculate depends (does not depend) on the density of the wood.
2) A wooden block with a volume of x x
cm
3
floats on water. What is the volume of the wood above the water level if the density of the wood is
g/cm
3
(see sheet 20)
? Indicate with a negative (positive) sign whether this fraction is zero (greater than zero) if the density of the wood is greater than the density of water.
3) The flow rate of a fluid through a pipe with a cross sectional area of
cm
2
is
liters per second
. What is the speed of the fluid
(see sheet 25).
Indicate with a positive (negative) sign whether the expression you use is valid for a fluid that cannot be (can easily be) compressed.
4) Water flows through a pipe vertically upward. The pipe has the same cross sectional area everywhere. You mark two points on the pipe, one
m
higher than the other. What is the pressure difference between bottom and top points inside the pipe
(see sheet 29;
hint: what does the equation on
sheet 25
tell you about the velocities ?
)
? Indicate with a positive (negative) sign whether your result depends (does not depend) on the velocity of the water flow.
5) You mark two points on a water pipe which is horizontally positioned with water flowing through it from left to right. The diameter of the pipe at the left mark is
cm
and at the right mark is
cm
. What is the pressure difference between left and right
(see sheet 29,25)
if the velocity of the fluid on the left is
cm/s
? Now tilt the pipe such that the right mark is higher than the left mark and indicate with a negative (positive) sign whether the pressure difference increases (decreases).
6) A fluid with a given viscosity flows through a cylindrical vessel. You reduce the vessel radius by a factor (divide by this factor). If the pressure difference is the same as before what is the ratio of the new flow rate over the old flow rate
(see sheet 36,38)
? Indicate with a negative (positive) sign whether the pressure difference has to be increased (decreased) in order to maintain the same flow rate as before the radius reduction.
Once you have submitted your answers for grading by clicking the grade button, you
cannot resubmit answers
for the same Problem Set--you must use the 'New Problems' button first.