olympiad_2008_fnet_ma

4 point.There is no penalty for leaving an answer blank.

?A hand-held calculator may be used.Its memory must be cleared of data and programs.You may use only the basic functions found on a simple scienti?c calculator.Calculators may not be shared.Cell phones may not be used during the exam or while the exam papers are present.You may not use any tables,books,or collections of formulas.

?This test contains25multiple choice questions.Your answer to each question must be marked on the optical mark answer sheet that accompanies the test.Only the boxes preceded by numbers1through25are to be used on the answer sheet.

?All questions are equally weighted,but are not necessarily the same level of di?culty.?In order to maintain exam security,do not communicate any information about the questions(or their answers or solutions)on this contest until after February 20,2008.

?The question booklet and answer sheet will be collected at the end of this exam.You may not use scratch paper.

DO NOT OPEN THIS TEST UNTIL YOU ARE TOLD TO BEGIN

2m (b)33

√3m

(d)3m

(e)9m

3.The position vs.time graph for an object moving in a straight line is shown below.What is the instantaneous velocity at t =2s?

24

3

21

?2P o s i t i o n (m )Time (s)

(a)?2m /s

(b)?1

6above the

horizontal?Ignore air resistance.

(a)√2

L

(b)1

2

L

(c)1

3

L

(d)1

3

L

7.A toboggan sled is traveling at2.0m/s across the snow.The sled and its riders have a combined

mass of120kg.Another child(m child=40kg)headed in the opposite direction jumps on the sled from the front.She has a speed of5.0m/s immediately before she lands on the sled.What is the new speed of the sled?Neglect any e?ects of friction.

(a)0.25m/s

(b)0.33m/s

(c)2.75m/s

(d)3.04m/s

(e)3.67m/s

8.Riders in a carnival ride stand with their backs against the wall of a circular room of diameter

8.0m.The room is spinning horizontally about an axis through its center at a rate of45rev/min

when the?oor drops so that it no longer provides any support for the riders.What is the minimum coe?cient of static friction between the wall and the rider required so that the rider does not slide down the wall?

(a)0.0012

(b)0.056

(c)0.11

(d)0.53

(e)8.9

3.05 3.45

4.05 4.45

5.05

0.0950.2050.2950.4050.495

10.Which is the best value for the mass of the block?

(a)3kg

(b)5kg

(c)10kg

(d)20kg

(e)30kg

11.Which is the best value for the coe?cient of friction between the block and the surface?

(a)0.05

(b)0.07

(c)0.09

(d)0.5

(e)0.6

E

2 (b)3

A

2

A (b)1

2

√(c)

2E

(b)2E

√(c)2

v

2

v (b)1

2 (c)v

√(d)

a0

2

a0 (b)1

2 (c)a0

√(d)

E

(b)2ρgh

22Lh (d)

3Eh 2

(e)√ρgh

21.Consider a particle at rest which may decay into two (daughter)particles or into three (daughter)

particles.Which of the following is true in the two-body case but false in the three-body case?(There are no external forces.)

(a)The velocity vectors of the daughter particles must lie in a single plane.

(b)Given the total kinetic energy of the system and the mass of each daughter particle,it

is possible to determine the speed of each daughter particle.

(c)Given the speed(s)of all but one daughter particle,it is possible to determine the speed

of the remaining particle.

(d)The total momentum of the daughter particles is zero.

(e)None of the above.

22.A bullet of mass m 1strikes a pendulum of mass m 2suspended from a pivot by a string of length

L with a horizontal velocity v 0.The collision is perfectly inelastic and the bullet sticks to the bob.Find the minimum velocity v 0such that the bob (with the bullet inside)completes a circular vertical loop.

(a)2

√5Lg

(c)(m 1+m 2)2

√Lg/m 2(e)(m 1+m 2)√

g

1

g

r

g

1?r g

1 g

1

2v0.What is the minimum

distance between the second satellite and the planet over the course of its orbit?

(a)1

2

R

(b)1

3

R

(d)1

7

R

Copyright c 2008American Association of Physics Teachers

2008F=ma Exam11