Spring 2000 Physics 101 Hour Exam 3
(25 questions)

The grading button and a description of the scoring criteria are at the bottom of this page. Basic questions are marked by a single star *. More difficult questions are marked by two stars **. The most challenging questions are marked by three stars ***

This exam consists of 25 questions; true-false questions are worth 2 points each, three-choice multiple choice questions are worth 3 points each, five-choice multiple choice questions are worth 6 points each. The maximum possible score is 111. When the exam was given, the minimum "A" score was 99; the minimum "B" was 85; the minimum "C" was 72; the minimum "D" was 55. The mean was 96.4; the median was 98. Click here to see the formula sheet that came with the exam.


QUESTION 1*

This and the next three questions pertain to the following situation:

A block of mass 6.0 kg resting on a horizontal frictionless surface is attached to a spring with force constant k=210 N/m. A force of F is applied to the block in the x-direction, thereby compressing the spring from its equilibrium length by (see picture) by 0.1m.

What is the magnitude of force F?

(a)   8 N
(b)   10 N
(c)   17 N
(d)   13 N
(e)   21 N


QUESTION 2*

The force is removed and the block starts to oscillate. What is the period of this oscillation?

(a)   3.3 sec
(b)   2.3 sec
(c)   1.1 sec
(d)   1.4 sec
(e)   9.3 sec


QUESTION 3*

If the initially applied force were doubled to 2F, how would the oscillation frequency of the block change?

(a)   It would be twice as large.
(b)   It would be four times as large.
(c)   It would not change.


QUESTION 4**

Now consider that we use two such identical springs in parallel as shown in the figure and we apply the same initial force F. How is the oscillation period different in this case?

(a)   It will be larger.
(b)   It will be smaller.
(c)   It will not change.


QUESTION 5*

This and the next question pertain to the following situation:

An Archer pulls the bowstring back a distance of 0.2 m before releasing the arrow. Consider that the bow and string act like a spring with a spring constant of 230 N/m. The arrow has a mass of 0.03 kg.

What is the magnitude of the spring potential energy of the drawn bow?

(a)   2.3 J
(b)   4.6 J
(c)   9.2 J
(d)   3.4 J
(e)   8.2 J


QUESTION 6*

What is speed of the arrow when it leaves the bow?

(a)   8.5 m/s
(b)   10.2 m/s
(c)   17.5 m/s
(d)   13.3 m/s
(e)   19.4 m/s


QUESTION 7**

Two pendulums start out swinging together. After 10 seconds, the first pendulum with length L1 has completed 10 cycles, while the second one with length L2 has finished 5 cycles. What is the ratio of L2 to L1?

(a)   L2 / L1 = sqrt(2)
(b)   L2 / L1 = 2
(c)   L2 / L1 = 4


QUESTION 8*

An ice cube floats in a glass of water. What happens to the level of the water when the ice melts?

(a)   It rise.
(b)   It stays the same.
(c)   It falls.


QUESTION 9***

An ice cube floats in a glass of syrup whose density is greater than that of water. What happens to the level of the liquid in the glass when the ice melts?

(a)   It rise.
(b)   It stays the same.
(c)   It falls.


QUESTION 10**

You have two bricks of the same volume, one made of lead and one made of iron. The density of lead is larger than that of iron and both are larger than that of water. You put both bricks into a pool of water. Compare the buoyant force on the lead brick FB, LEAD to the buoyant force on the iron brick, FB, IRON .

(a)   FB, LEAD = FB, IRON
(b)   FB, LEAD > FB, IRON
(c)   FB, LEAD < FB, IRON


QUESTION 11*

This and the next question pertain to the following situation:

A block of mass 10 kg and volume 1.25 x 10-3 m3 is suspended from a string and immersed in water (density = 1000 kg/m3) as shown in the figure.

How large is the buoyant force on the block?

(a)   4.07 N
(b)   9.26 N
(c)   12.3 N
(d)   47.8 N
(e)   98.1 N


QUESTION 12*

Suppose the answer to the preceding question is FB. What is the tension in the string (in Newtons)?

(a)   98
(b)   98 + FB
(c)   98 - FB


QUESTION 13*

The small piston of a hydraulic lift has a cross sectional area of 3 cm2 and the large piston has an area of 200 cm2. What force F must be applied to the small piston to lift a load of 15,000 N on the large piston, assuming both pistons are at the same height, as shown in the drawing?

(a)   150 N
(b)   225 N
(c)   550 N
(d)   1050 N
(e)   2.25 × 108 N


QUESTION 14*

This and the next question pertain to the following situation:

Water (density = 1000 kg/m3) squirts from a syringe at a speed of 30 m/s. The diameter of the opening is 1 x 10-4 m.

What is the mass of the water that flows through the hole in one second?

(a)   2.4 × 10-4 kg
(b)   5.1 × 10-4 kg
(c)   7.2 × 10-4 kg
(d)   8.5 × 10-4 kg
(e)   10.2 × 10-4 kg


QUESTION 15*

What is the pressure difference between the water inside the syringe and the air outside? You may assume that the flow speed inside the syringe is 0.1m/s.

(a)   4.5 × 105 N/m2
(b)   5.3 × 105 N/m2
(c)   7.2 × 105 N/m2
(d)   8.4 × 105 N/m2
(e)   9.7 × 105 N/m2


QUESTION 16*

You have an insulated cup containing 160 g of coffee at a temperature 90°C. You add to it 10 g of milk with a temperature of 10°C. Assuming the specific heat of the coffee and milk are the same (and equal to that of water), what is the final temperature of the mixture?

(a)   5°C
(b)   30°C
(c)   45°C
(d)   65°C
(e)   85°C


QUESTION 17*

This and the next question pertain to the following situation:

A barometer is filled with an unknown liquid as shown in the drawing below. The open bottom end of the barometer is exposed to air at atmospheric pressure Pa=1.01 x 105 N/m2, and the pressure in the top closed end is 0. The liquid in the closed end rises to a height h0=1.5 m above the open end. What is the density of the liquid?

(a)   2510 kg/m3
(b)   3250 kg/m3
(c)   6870 kg/m3
(d)   7630 kg/m3
(e)   9340 kg/m3


QUESTION 18*

Now suppose that the pressure at the closed end of the barometer is Pa/2 rather than 0. To what height h1will the liquid rise (assume itís the same liquid as in the above problem).

(a)   h1 = h0
(b)   h1 = h0 / 2
(c)   h1 = h0 / 4


QUESTION 19*

An aluminum plate has a circular hole cut in it. A steel ball (solid sphere) has exactly the same diameter as the hole when both are at room temperature, and hence can just barely be pushed through it. If both the plate and the ball are now heated up to a few hundred degrees Celsius, how will the ball and the hole fit?

(a)   The ball wonít fit through the hole any more.
(b)   The ball will fit more easily through the hole.
(c)   Same as at room temperature.


QUESTION 20*

This and the next question pertain to the following situation:

Two metal rods, one made from aluminum and the other from steel, have the same initial length (Lo = 5 m) at room temperature (To = 20°C). At what temperature T1 would the aluminum rod be 2 mm longer than the steel rod (assuming that both rods are at the same temperature).

(a)   T1 = -22°C
(b)   T1 = 0°C
(c)   T1 = 4°C
(d)   T1 = 56°C
(e)   T1 = 88°C


QUESTION 21*

Suppose the answer to the above question is T1. If just the aluminum rod is held at temperature T1 and the steel rod remains at room temperature T0, the difference in lengths between the rods will be

(a)   greater than 2 mm.
(b)   less than 2 mm.
(c)   equal to 2 mm.


QUESTION 22**

A 5 kg block of aluminum and a 5 kg block of steel are both at an initial temperature of 10°C. Both are placed into identical (but separate) insulated buckets of water, each bucket containing 10kg of water initially at 90°C. Assuming no heat leaves the buckets, which one contains the warmest water after a long time?

(a)   The bucket with the aluminum block.
(b)   The bucket with the steel block.
(c)   Both buckets of water will be at the same temperature.


QUESTION 23*

This and the next question pertain to the following situation:

A 50 g ice cube having an initial temperature of 0°C is put into an insulated cup containing a mass M of water that has an initial temperature of 20°C. After a long time, all the ice is melted and the remaining water is at 0°C. What was the mass M of the water that was initially in the cup? (Assume no heat can flow in or out of the cup)

(a)   M = 50 g
(b)   M = 115 g
(c)   M = 135 g
(d)   M = 180 g
(e)   M = 200 g


QUESTION 24**

If the initial temperature of the water in the cup were 10°C rather than 20°C, but everything else (i.e. the mass of the water and the ice) were the same as above, which of the following statements would best describes the contents of the cup after a long time?

(a)   A mixture of water and ice at a temperature of 0°C.
(b)   Water at a temperature of 0°C.
(c)   Ice at a temperature of 0°C.


QUESTION 25**

Compare the volume of 1kg of water at 0°C, V0, to the volume of 1kg of water at 4°C, V4.

(a)   V0 = V4
(b)   V0 > V4
(c)   V0 < V4