Physics A Exam 3: Problem Solving Session, Exams of Physics

A physics exam from october 25/26, 2001, consisting of 5 problems. Students are required to calculate various physical quantities such as acceleration, net force, free-body diagrams, and tension in ropes. The exam covers topics like newton's laws, friction, and forces acting on objects. Students are expected to show their work and follow rules regarding significant figures and units.

Typology: Exams

Pre 2010

Uploaded on 07/30/2009

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Physics A Exam 3 12/05/20
PHYSICS A
EXAM 3
October 25/26, 2001
Name:___________________
Rules for Exam:
1. Crib sheet will be provided by instructor.
2. Calculators are allowed, but you may not share one.
3. Show your work on numerical problems. Do not expect any credit for a
problem if I cannot logically follow what you have put on your paper.
4. Follow the rules for significant figures. One point will be deducted for every
two infractions.
5. Make sure you include units with each answer. One point will be deducted
for each infraction.
6. Points will be deducted for students that refuse to turn in their exams, when
asked to do so (at the end of class).
7. Circle your final answers.
________________________________________________________
Conversion Factors:
1 mile= 5280 feet (exact) 1 day= 24 hours (exact)
1 km =0.6214 miles 1 year=365.25 days
1 inch= 2.54 cm (exact) 1 hour=60 minutes (exact)
1 gallon =3.785 liters=231 in31 km=1000 meters (exact)
1 slug=14.59 kg 1 foot= 12 inches
1 mile= 1609.3 m 1 parsec=3.26 light-years
1 meter=39.37 inches 1lb=0.454kg
1 cm=0.01meters=10 mm (exact) 1ft=30.48cm
1 minute= 60 seconds (exact)
SCORE
PROBLEM 1 (20 points)
PROBLEM 2 (20 points)
PROBLEM 3 (30 points)
PROBLEM 4 (20 points)
PROBLEM 5 (14 points)
TOTAL (104 max)
PERCENTAGE OUT OF 100
Solve the problems you think are easiest first.
1
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pf4
pf5

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PHYSICS A

EXAM 3

October 25/26, 2001

Name:___________________

Rules for Exam:

1. Crib sheet will be provided by instructor.

2. Calculators are allowed, but you may not share one.

3. Show your work on numerical problems. Do not expect any credit for a

problem if I cannot logically follow what you have put on your paper.

4. Follow the rules for significant figures. One point will be deducted for every

two infractions.

5. Make sure you include units with each answer. One point will be deducted

for each infraction.

6. Points will be deducted for students that refuse to turn in their exams, when

asked to do so (at the end of class).

7. Circle your final answers.

________________________________________________________

Conversion Factors: 1 mile= 5280 feet (exact) 1 day= 24 hours (exact) 1 km =0.6214 miles 1 year=365.25 days 1 inch= 2.54 cm (exact) 1 hour=60 minutes (exact) 1 gallon =3.785 liters=231 in^3 1 km=1000 meters (exact) 1 slug=14.59 kg 1 foot= 12 inches 1 mile= 1609.3 m 1 parsec=3.26 light-years 1 meter=39.37 inches 1lb=0.454kg 1 cm=0.01meters=10 mm (exact) 1ft=30.48cm 1 minute= 60 seconds (exact) SCORE PROBLEM 1 (20 points) PROBLEM 2 (20 points) PROBLEM 3 (30 points) PROBLEM 4 (20 points) PROBLEM 5 (14 points) TOTAL (104 max) PERCENTAGE OUT OF 100

Solve the problems you think are easiest first.

  1. A physics instructor places a fire extinguisher on a little red wagon. She then sits in it. She presses the handle and off she goes. Her speed went from zero to 2.42m/s in 4.23s. The average thrust of the fire extinguisher was measured to be 75N. The total mass of the instructor, wagon and fire extinguisher is 75kg. a. What was the average acceleration of the wagon? (4 points) Ans 0.572m b. What is the net force that produced this acceleration? Which law did you use for this calculation? (6 points) Ans 43N c. Draw a free-body diagram for the vehicle. You must indicate and label all forces acting on the objects. Using your free body diagram and Newton’s law(s) calculate the magnitude of the frictional force acting on the wagon. (10 points) Ans 32N
  1. A 120kg object is suspended by the two cables as shown in the figure below. a. Draw a free-body diagram indicating all the forces acting on the knot connecting the three cables. Also, Indicate all the forces acting directly on the mass. Make sure you also show the components of all forces. (12 points) Ans see instructor b. Write down the equations for the sum of the forces in the x and y-directions and solve for the tension in all three strings. Be sure to include all terms. You MUST show your work. (18 points) Ans 710N and 940N 120kg 37 o 53 o 37 o

Name:___________________

  1. A force F pulls on a 3.22 kg object on a table. Assume there is no friction between the table and the object. a. Draw a free-body diagram indicating all the forces acting on the block. Indicate the direction of each component of each force. (8 points) Ans see instructor b. Calculate the normal force acting on the object. (6 points) Ans 16N c. Calculate the object’s acceleration in the horizontal direction. (6 points) Ans 6.2m/s/s

37 o

3.22kg

25N