### Physics Exam

1. A football field is 120 yd long and 50 yd wide. What is the area of the football field, in m2, if 1 yd = 91. 44 cm? (Points : 5) [pic]5. 0 x 103 m2 [pic]2. 4 x 103 m2 [pic]4. 2 x 103 m2 [pic]3. 7 x 103 m2 | | |2. Suppose that an object travels from one point in space to another. Make a comparison between the displacement and the distance| |traveled. (Points : 5) | | [pic]The displacement is either greater than or equal to the distance traveled. | [pic]The displacement can be either greater than, smaller than, or equal to the distance traveled. | | [pic]The displacement is always equal to the distance traveled. | | [pic]The displacement is either less than or equal to the distance traveled. | |3. A bullet moving horizontally to the right (+x direction) with a speed of 500 m/s strikes a sandbag and penetrates a distance | |of 10. 0 cm. What is the average acceleration, in m/s2, of the bullet? (Points : 5) | | [pic]-1. 5 x 103 | | [pic]-1. 25 x 106 | | [pic]-2. 50 x 103 | | [pic]-2. 50 x 106 | |4. An airplane increases its speed from 100 m/s to 160 m/s, at the average rate of 15 m/s2.

How much time does it take for the | |complete increase in speed? (Points : 5) | | [pic]17 s | | [pic]4. 0 s | | [pic]0. 058 s | | [pic]0. 25 s | |5.

A bullet is fired horizontally, and at the same instant a second bullet is dropped from the same height. Ignore air | |resistance. Compare the times of fall of the two bullets. (Points : 5) | | [pic]The fired bullet hits first. | | [pic]They hit at the same time. | | [pic]The dropped bullet hits first. | | [pic]cannot tell without knowing the masses | |6. Starting from rest, a 4. 0-kg body reaches a speed of 8. m/s in 2. 0 s. What is the net force acting on the body? (Points : 5) | | [pic]4. 0 N | | [pic]32 N | | [pic]16 N | | [pic]8. 0 N | |7. A spring is characterized by a spring constant of 60 N/m. How much potential energy does it store, when stretched by 1. | |cm? (Points : 5) | | [pic]60 J | | [pic]600 J | | [pic]3. 0 x 10-3 J | | [pic]0. 30 J | |8. A 2. 0-kg softball is pitched to you at 20 m/s.

You hit the ball back along the same path, and at the same speed. If the bat | |was in contact with the ball for 0. 10 s, what is the magnitude of the average force the bat exerted? (Points : 5) | | [pic]400 N | | [pic]40 N | | [pic]zero | | [pic]800 N | 9. A wheel of diameter of 68. 0 cm slows down uniformly from 8. 40 m/s to rest over a distance of 115 m. How long does it take for | |the wheel to come to the stop? (Points : 5) | | [pic]42. 7 s | | [pic]27. 4 s | | [pic]47. s | | [pic]24. 7 s | |10. A book weighs 6 N. When held at rest above your head the net force on the book is (Points : 5) | | [pic]9. 8 N | | [pic]0 N | | [pic]6 N. | | [pic]-6 N. | |11. 50 cm3 of wood is floating on water, and 50 cm3 of iron is totally submerged. Which has the greater buoyant force on | |it? Points : 5) | | [pic]the iron | | [pic]the wood | | [pic]Both have the same buoyant force. | | [pic]cannot be determined without knowing their densities | |12. In a hydraulic garage lift, the small piston has a radius of 5. 0 cm and the large piston has a radius of 15 cm.

What force | |must be applied on the small piston in order to lift a car weighing 20,000 N on the large piston? (Points : 5) | | [pic]5. 0 x 103 N | | [pic]6. 7 x 103 N | | [pic]2. 2 x 103 N | | [pic]2. 9 x 103 N | 13. A brick weighs 50. 0 N, and measures 30. 0 cm x 10. 0 cm x 4. 00 cm. What is the maximum pressure it can exert on a horizontal | |surface? (Points : 5) | | [pic]12. 5 Pa | | [pic]1. 25 kPa | | [pic]12. 5 kPa | | [pic]1. 5 Pa | |14. A liquid has a specific gravity of 0. 357. What is its density? (Points : 5) | | [pic]643 kg/m3 | | [pic]357 kg/m3 | | [pic]3570 kg/m3 | | [pic]1000 kg/m3 | |15.

The frequency of a wave increases. What happens to the distance between successive crests if the speed remains | |constant? (Points : 5) | | [pic]It increases. | | [pic]It decreases. | | [pic]It remains the same. | | [pic]It cannot be determined from the information given. | |16. What is the wave speed if a wave has a frequency of 12 Hz and a wavelength of 3. 0 m? (Points : 5) | | [pic]4. m/s | | [pic]15 m/s | | [pic]36 m/s | | [pic]9. 0 m/s | |17. An object in simple harmonic motion obeys the following position versus time equation: y = (0. 50 m) sin (? /2 t). What is the | |amplitude of vibration? (Points : 5) | | [pic]0. 0 m | | [pic]1. 0 m | | [pic]0. 25 m | | [pic]0. 75 m | |18. On a day when the speed of sound in air is 340 m/s, a bat emits a shriek whose echo reaches it 0. 0250 s later. How far away | |was the object that reflected back the sound? Points : 5) | | [pic]4. 25 m | | [pic]0. 850 m | | [pic]0. 425 m | | [pic]8. 50 m | |19. A barking dog delivers about 1 mW of power, which is assumed to be uniformly distributed in all directions.

What is the | |intensity level at a distance 5. 00 m from the dog? (Points : 5) | | [pic]68 dB | | [pic]61 dB | | [pic]65 dB | | [pic]63 dB | |20. The wavelengths of the sounds produced by two horns are 6 m and 7 m respectively.

What beat frequency is heard when the horns| |are sounded on a day when the velocity of sound is 340 m/s? (Points : 5) | | [pic]8 Hz | | [pic]6 Hz | | [pic]5 Hz | | [pic]7 Hz |