Quizzes > Engp Q4 02

UNIVERSITY OF SOUTH AUSTRALIA Applied Physics - School of Electrical & Information Engineering ENGINEERING PHYSICS QUIZ 4 [ week 9 ] Time: 20 minutes

Name .....................................................................................

QUESTIONS ( 7 MARKS )

Marks: /15

ANSWERS

1. An object is given a push and it moves along a horizontal surface. What is the effect of the force of friction as the object moves? A. it does positive work on the object, B. it increased the object’s kinetic energy, C. it increases the objects potential energy, D. none of the above.

2. The prefix giga represents … A. B. C. D.

10-9, 10+9, 10-12, 10+12.

3. An aircraft comes in for a crash landing as it can not lower the landing gear. As it slides along the tarmac on it’s undercarriage, which force does the most work? A. the normal force, B. the frictional force, C. neither A or B do any work, D. either A or B depending on the value of µk.

4. You are coming in to land your Kendell’s Airlines aircraft at Adelaide airport and hit a seagull flying in the

opposite direction square in the middle of the pilot’s front window. Without all the gruesome details, the bird sadly was deceased and the window remained intact. We then know that, A. the force of the bird on the glass was bigger than the force of the glass on the bird, B. the force of the bird on the glass was the same as the force of the glass on the bird, C. the force of the bird on the glass was less than the force of the glass on the bird, D. the aircraft didn’t slow down as it hit the bird.

5. The total kinetic energy of a spinning object moving through the air (ie. a frisbee or a spinning baseball) is a function of which of the following? A. it’s linear velocity but not angular velocity, B. it’s angular velocity but not linear velocity, C. both linear and angular velocity, D. neither linear nor angular velocities.

6. A flywheel on a power generating turbine is spinning at a rate of 10 revolutions per second. What is it’s approximate angular velocity? … A. 62 rad/s, B. 10π rad/s, C. 3.14159 rad/s, D. none of the above.

7. When positive work is done on a system by the total force on it, then … A. B. C. D.

it’s kinetic energy increases, it’s potential energy decreases, the sum of kinetic & potential energy increases, the sum of its kinetic and potential energy must remain constant.

PROBLEMS ( 9 MARKS ) Question 1 (3 marks) Compare a small raindrop and a large raindrop falling through the atmosphere. Compare their terminal speeds. What are their accelerations when they reach terminal speed? ………………………………………..…………………………………………………………………………… ………………………………………..…………………………………………………………………………… ………………………………………..…………………………………………………………………………… ………………………………………..…………………………………………………………………………… ………………………………………..…………………………………………………………………………… ………………………………………..…………………………………………………………………………… ………………………………………..…………………………………………………………………………… ………………………………………..……………………………………………………………………………

Problem 1 (4 marks) An archer pulls her bow string back 0.4 m by exerting a force that increases uniformly from zero to 230 N. (i) What is the equivalent spring constant of the bow? ………………………………………………..………………………………………………………………………… … ………………………………………………..………………………………………………………………………… … ………………………………………………..………………………………………………………………………… … ………………………………………………..………………………………………………………………………… … ………………………………………………..………………………………………………………………………… … ………………………………………………..………………………………………………………………………… … (ii) How much work is done in pulling the bow string back? ………………………………………………..………………………………………………………………………… … ………………………………………………..………………………………………………………………………… … ………………………………………………..………………………………………………………………………… … ………………………………………………..………………………………………………………………………… … ………………………………………………..………………………………………………………………………… … ………………………………………………..………………………………………………………………………… … Problem 2 (2 marks) A 6 kg bowling ball moves at 3.00 m/s down a bowling lane. How fast must a 46 g golf ball move so that the two balls have the same kinetic energy?

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