Quizzes > Engp Q2 02

UNIVERSITY OF SOUTH AUSTRALIA Applied Physics - School of Electrical & Information Engineering ENGINEERING PHYSICS QUIZ 2 [ week 5 ] Time: 20 minutes

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

Marks: 18/15

QUESTIONS ( 8 MARKS )

ANSWERS

1. Which of the following has 3 significant figures? A. 123.000 B. 1.23x1027 C. 0.123 D. 3.123

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

1000, 1,000,000, 1010, 1,000,000,000.

3. A health conscious student on a bicycle travels 12 km in 40 minutes. The average speed of the student is … A. B. C. D.

0.3 km/hr, 8 km/hr, 18 km/hr, 48 km/hr.

4. A juggler throws two balls to the same height so that one is at the halfway point going up when the other is at the halfway point coming down. At that point, assuming air resistance is negligible .. A. their velocities and accelerations are equal, B. their velocities are equal but their accelerations are equal and opposite, C. their accelerations are equal but their velocities are equal and opposite, D. their velocities and accelerations are both equal and opposite.

5. An object weighing 200 N hangs motionless from a string attached to the ceiling. The net force on the object is … A. B. C. D.

zero, approximately 20 N, approximately 2000 N, exactly 200 N.

6. Which statement is true about the unit vectors i, j and k? A. B. C. D.

j x i = k, i x i is meaningless, i x j = j x i, If i is directed west and j is directed perpendicular to the earths surface, k points north.

7. The centripetal force needed to keep the space shuttle in orbit around the earth is provided by … A. B. C. D.

constantly rotating the shuttle, booster rockets, the gravitational force between the moon and the earth, the gravitational force between the shuttle and the earth.

8. In order to cause a moving object to follow a circular path, it is necessary to apply … A. B. C. D.

an inertial force, a frictional force, a gravitational force, a centripetal force.

PROBLEMS ( 10 MARKS ) Question 1 (4 marks) Is it possible for a vehicle to travel around a curve without accelerating? Explain. ………………………………………..…………………………………………………………………………… ………………………………………..…………………………………………………………………………… ………………………………………..…………………………………………………………………………… ………………………………………..…………………………………………………………………………… ………………………………………..…………………………………………………………………………… ………………………………………..…………………………………………………………………………… ………………………………………..…………………………………………………………………………… ………………………………………..……………………………………………………………………………

Problem 1 (6 marks) You are on a ledge in the dark and wish to estimate the height of the ledge above the ground. You take a shoe off and drop it over the edge and hear it strike the ground 1 s later. (i) What is the height of the ledge?

1 ………………………………………..…………………………………………………………………………… s = v0 t +

at 2 2 ………………………………………..…………………………………………………………………………… v f = v 0 + at ………………………………………..…………………………………………………………………………… ………………………………………..…………………………………………………………………………… v 2f = v 02 + 2as ………………………………………..…………………………………………………………………………… ………………………………………..…………………………………………………………………………… (ii) How could you use your other shoe to estimate the height of the ledge if you were timid and not close enough to the edge to simply drop the shoe. Explain what you would have to do to obtain a meaningful result. Draw a diagram of the two situations. ………………………………………..…………………………………………………………………………… ………………………………………..…………………………………………………………………………… ………………………………………..…………………………………………………………………………… ………………………………………..……………………… ………………………………………..……………………… ………………………………………..……………………… ………………………………………..……………………… ………………………………………..……………………… ………………………………………..……………………… ………………………………………..……………………… ………………………………………..……………………… ………………………………………..………………………