Quizzes > Engp Quiz2 04

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

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

MULTIPLE CHOICE QUESTIONS ( 12 MARKS )

Marks:

/20 ANSWERS

1. Which statement below is FALSE? A. B.

Y = FLo/A∆L S = Fh/A∆x,

C. D.

B = FVo/A∆V, One of the above statements is wrong.

2. 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.

3. Which statement below is FALSE? A. B.

i = j x k, FB = qB x v,

D.

C. r x p = -(p x r), τ = r x F.

4. Tensile stress is defined as: A. B. C. D.

∆L/L where L is the length, F/L where F is the tension force and L is the length, Y(∆L) where Y is Youngs modulus and L is length, F/A where F is the tension force and A is the cross-sectional area.

5. In mechanical equilibrium, an object must have, A. B. C. D.

constant acceleration, no forces acting on it, no translational or rotational acceleration, none of the above.

6. What is the buoyancy force of a fluid upon an object that sinks in the fluid? A. B. C.

zero, an upward force equal in magnitude to that of the weight of the object, an upward force equal in magnitude to the magnitude of the weight of a quantity of fluid equal to the objects volume.

7. A Tae Kwon Do black belt executes a swift knife hand chop and breaks 2 cement roofing tiles. The magnitude is the same for the … A. force on both the tiles and the black belts hand, B. impulse on both the tiles and the hand, C. time of impact on both the tiles and the hand, E. all of the above.

8. If a uniform, heavy cable is suspended from one end, the cable is most likely to break from its own weight at a point A. B. C. D.

near its top end where it is suspended, near its bottom end, near the middle, anywhere along its length.

9. Astronauts in spacecraft on the way to the moon or orbiting the earth have been described as being in a

“weightless” or “zero-g” condition because … A. they have no mass at this point, B. they are beyond the range of the Earth’s gravity, C. both they and their spacecraft move and accelerate together, D. the spacecraft is covered with a special alloy which does not allow the gravitational field to penetrate. 10. The velocity of sound in water is… A. dependant on the bulk modulus of water,

B. C. D.

dependant on the temperature of the water, greater than the velocity of sound in air, all of the above.

11. 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.

12. Different isotopes of an element contain, A. B. C. D.

the same number of neutrons but different number of electrons. the same number of electrons but different number of protons. the same number of protons but different number of neutrons. the same number of nucleons.

QUESTIONS & PROBLEMS ( 10 marks possible)

P+

1 2 ρv + ρgh = constant 2

Question 1 (4 marks) Use Bernoulli’s Principle to explain qualitatively how an airplane wing develops an upward lift. When landing, airplanes head into the wind. Explain why. Remember, pressure is force per unit area. ………………………………………..…………………………………………………………………………… ………………………………………..…………………………………………………………………………… ………………………………………..…………………………………………………………………………… ………………………………………..…………………………………………………………………………… ………………………………………..…………………………………………………………………………… ………………………………………..…………………………………………………………………………… ………………………………………..…………………………………………………………………………… Problem 1 (3 marks) An average person (mass 70kg) rock climbing slips from a ledge, hangs in free air from a slim nylon rope with a length of 20m, a cross sectional area of 1.00 cm2, and a Young’s modulus of 1.0 x 1010 N/m2. What is the increase in length of the rope from it’s un-stressed form? ………………………………………..…………………………………………………………………………… ………………………………………..…………………………………………………………………………… ………………………………………..…………………………………………………………………………… ………………………………………..…………………………………………………………………………… ………………………………………..…………………………………………………………………………… ………………………………………..…………………………………………………………………………… Problem 2 (3 marks) A 6.00 kg bowling ball moves at 3.00 m/s down a bowling lane. How fast must a 40 g golf ball move so that the two balls have the same kinetic energy? ………………………………………………..………………………………………………………………………… … ………………………………………………..………………………………………………………………………… … ………………………………………………..………………………………………………………………………… … ………………………………………………..………………………………………………………………………… …

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