4 Problems on University Physics I - Old Final Exam Fall 1999 | PHYS 2050, Exams of Physics

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XF.

PHYS-205(3) (Kaldon-21354)

Name _______S A M P L E __ F I N A L __ E X A M____

Final Exam - 200,000 points + 40,000WMU - Spring 1999

(^)
(^) points

Check-Out:

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X

T

___

6/22/1999•Rev.5c·04/09/2006•r5d

State Any Assumptions You Need To Make – Show All Work – Circle Any Final Answers Use Your Time Wisely – Work on What You Can – Be Sure to Write Down Equations

Feel Free to Ask Any Questions

2a

2b

2c

2e

(a) Find the average speed of Mr. Greene during his run.world’s record in the 100 meter dash at a track meet in Athens, Greece. 1.) 9.79 seconds. That’s where 24 year old Maurice Greene recently set the World’s Fastest Human (Self-Powered, On-Foot) (50,000 points)

problem?meters, find his acceleration. What assumption must you make to solve thisjust a few strides. If Mr. Greene goes from rest to 9.00 m/s in a distance of 5.00(b) Sprinters need to get up to near their top speed in

At this level of competition, sprinters use

(^) starting blocks

(^) to get themselves moving. The vector force

1^ F

is applied at a standard angle of 220°. This is the force that the

(^) runner

(^) applies to the starting block. (c) In

what direction does the force

2^ F

(^) , the force

(^) on the runner

, point? (d) And why?

(e) Find the magnitude of the force

F

2

. Let

(^) m = 97.9 kg

.

In order to

of the force can we find from the information on this page?simplify the physics, do NOT use a Free Body Diagram – what part

Physics 205 / Final Exam

Spring 1999

Page 2

Odds and Ends

(50,000 points)

2.)

(a) A block of mass 50.0 kg slides along the floor on a frictionless layer of oil, with a kinetic energy

of 625 J. Unfortunately, the oil runs out and friction begins for form:

k^

L

x

.

, where

L

(^) is the

A velocity has an stopping distance for the block. Find L.

(^) x -component of

v x (t) = C t

(^5) , where

(^) C = 15 m/s

6

. At^

(^) t = 3.21 sec

(^) find

(b) (^) a x and

(c) (^) x . Assume x

(^0) and a

x (^) are both zero.

(d) Two masses,

(^) m (^1) and

(^) m 2 , are connected over a real pulley with moment of inertia,

I

, and radius

R

, and

where

(^) m 1 (^) < (^) m 2

. Setup the Free Body Diagrams for

(^) m 1 (^) and

(^) m (^2) , and the Free Rotation Diagram for the

pulley.

You must indicate which way the masses and the pulley intend

in this problem.to move, when the masses are released from rest. There is no friction (e) There is talk of building “elevators” that might take one into space. Imagine a steel wire stretching

be P =from the ground to 100,000 km above the ground. The pressure on the bottom of a column of steel would

gh under ordinary circumstances, but

(^) g (^) is not a constant here. To find the pressure from the

weight of the steel on the wire above, you need to integrate

P

g r dr

r r

z^

( )

(^12)

, where

(^) g(r)

(^) is from Newton’s

Universal Law of Gravity.

r 1 is the radius of the ground,

(^) r 2 is the radius of the orbit. Earth has a mass of

5.98 x 10

24 kg and a radius of 6378 km.^

G = 6.67 × 10

- N·m²/kg².^

steel (^) = 7130 kg/m³.

Physics 205 / Final Exam

Spring 1999

Page 3

Ta-Dah!!!

(50,000 points)

the dishes on a table, without breaking anything. Consider the plate, 3.) A fancy trick is to take a tablecloth and yank it out from underneath

(^) m =

0.425 kg

, and with coefficients of friction between the plate and

tablecloth of

0.

(^) and

0.

(^) respectively. Find (a) the maximum acceleration that the table cloth can

shatter. Are the forces that destroy these plates and glasses(e) If the trick is done badly, the plates and glassware will all crash to the ground where they smash and(d) If the tablecloth is snapped off the table in 11.0 ms (0.011 sec), how far does the plate move?the kinetic friction force between the plate and tablecloth.(c) Part of the secret of the trick is to yank the tablecloth such that it is moving very fast. Find the value ofwith the tablecloth.(b) Find the maximum constant speed that the table cloth can move to the right such that the plate travelsmove to the right such that the plate travels with the tablecloth.

(^) conservative

(^) forces? Why or why not? And

what one Physics word

(^) best

(^) describes all these ruined table settings?

Physics 205 / Final Exam

Spring 1999

Page 4

Heigh-Ho, Heigh-Ho, It’s Haul the Water We Go…

(50,000 points)

4.)

One gallon (U.S.) of water is 3.80 liters. Since there are 1000 L in 1.00 m³,

then 1.00 gal. = 3.80 × 10

m³. (a) Find the mass of this much water.^

(e) If actual efficiency, (d) Find the total work that the engine has to do, and the power it has to deliver.(c) Find the kinetic energy of the bucket.meters in 10.0 seconds. Find the change in the potential energy of the bucket.(b) Imagine that we have a bucket (m = 0.250 kg) with 1.00 gal. of water in it, and we wish to raise it 35.



actual

(^) , of the heat engine that is hauling up the bucket is 42.2% (0.422), then how

much energy is wasted when the bucket of water is brought up?