Transcript Fluid Resistance

All science is either physics or stamp collecting.
- Ernest Rutherford (1871 - 1937)
Discoverer of the nucleus
A car goes around a banked curve that is icy (frictionless).
The centripetal force is:
A] absent (not needed) because of the banking
B] the component of gravity acting toward the inside of the
curve
C] the component of the normal force acting toward the
inside of the curve
D] A combination of B&C
A greasy (frictionless) hand pushes two
blocks against a vertical wall.
There is static friction, coefficient ,
between the blocks and with the wall.
You wish to find out the minimum pushing
force to keep the blocks from slipping.
Take out a pencil and paper, and draw the
required FBD(s).
Which arrows show the
directions and relative
magnitudes of the frictional
forces on Block 2?
Fluid Resistance
C
A
B
Which curve could describe the (1D) velocity of a block sliding
down an inclined plane, as a function of time?
Any answer accepted. B is Best.
Which curve could describe the (1D) velocity of a skydiver, as a
function of time?
C
Assume the rate a car burns gas (in gallons/minute) is proportional to
the force the engine applies to the road (through the tires, of course.)
How much faster do you burn gas at a steady 80 mph vs at 40 mph?
Assume all resistance is air resistance.
A] You don’t burn gas because v is steady
B] Same rate per minute
C] Twice as fast
D] Four times as fast
E] Sixteen times as fast
Answer: D, since resistance increases with the square of velocity. Note: your
gas mileage would be half at 80 mph as at 40 mph. Why?
Forces acting on two particles are shown. The forces are
constant during the displacements shown.
Which force does no work?
A] F1A
B] F2A
C] F1B
D] F2B
E] They all do work
For which particle is the
total work done by all
forces = 0?
Choose A, B, or C
both=0.
A
Bonus Question: If the forces shown are the only forces
acting on the particles, which particle will change speed?
B will change its speed
and velocity!