Physics 213  Final Exam    16  Points Each Dec. 12, 2005

(Eight points absolutely FREE!)

 

1.   What is the launching speed of an object shot straight up if it only took 2 seconds to reach its maximum  height?

 

a. 10 m/s

 

b. 20 m/s

 

c. 30 m/s

 

d. 40 m/s

 

 

 

 

2.  A particle moves along the x axis according to the equation x = 2 + 3t - t2 .  Find its position, velocity, and acceleration at t = 3 s .

 

 

 

 

 

 

 

 

 

 

 

 

 

 

3.  While exploring a cave, a spelunker starts from the entrance and moves the following distances.  She goes 75 m north , then 250 m east, then 125 m at an angle of 37 ¡ north of east, and finally, 120 m south.  Find her resultant displacement from the cave entrance.  (Means find the sum of the given vectors.)  Leave answer in vector form.

 

 

 4.  A ball is tossed from an upper story window of a building .  The ball is given an initial velocity of 8 m/s at an angle of 37¡ below the horizontal.  It strikes the ground 3 seconds later. 

a.  How far horizontally from the base of the building does the ball strike the ground?

b.  How high is the window?

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

5.  A coin placed 30 cm from the center of a rotating horizontal turntable slips when its speed reaches 50 cm/s.  What  is the coefficient of static friction between coin and turntable?

 

6.  You are travelling in your 2000 kg Chevy at 20 m/s up a hill with a 6¡ incline when you see a goose crossing the road in front of you.  You hit the brakes when the goose is 24 m  away.  You know from previous experience that when you hit the brakes, a 16000 N friction force opposes your motion.  Will you hit the goose?

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

7. A 60 kg kid on a 200 kg bumper car is moving to the east at 80 m/s.  She has a head-on perfectly inelastic collision with another identical car that is moving west at 30 m/s and containing two large adults of equal mass.  The cars collide and stick together  and travel east at a speed of 8 m/s, how much do each of the adults weigh in newtons?

8. A solid sphere of mass 30 kg and radius 3 m rolls along the ground at 15 m/s as it approaches an incline.  (moment of inertia of a solid sphere is .4 m r2).

a.  If it doesn't reach the top of the incline, how far up the incline does it go ?

 

b.  If so, with what  speed does it strike the block?

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

9.  The Piano Lifter apparatus is still set up on one of the lab tables.  Draw a FBD for the meter stick.  Be sure to label all forces clearly.

 

10.  A 3 gram copper penny at 25.00 ¡ C drops 50 m to the ground.  Assuming that 60% of its change in potential energy of the earth-penny system goes into increasing the internal energy of the penny, determine its final temperature.  (Ignore air resistance.  Specific heat of copper is 390 J/Kg/C¡)

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

11.  An ideal gas initially at 300 K undergoes an isobaric expansion at 2.5 k Pa.  If the volume increases from 1 m2 to 3 m2 and 12.5 kJ is transferred to the gas by heat, what are  (a) the change in its internal energy and (b) its final temperature?

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

12.  A thermal window with an area of 6.00 m2 is constructed of two layers of glass, each 4.00 mm thick, and separated from each other by an air  space of 5.00 mm.  If the inside surface is at 20¡C and the outside surface is at -30¡C, what is the rate of energy transfer by conduction through the window?

 

Thermal conductivity  k (in J/s m C¡ ) of :

glass         .84

air .023