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) pic5. 0 x 103m2 pic2. 4 x 103m2 pic4. 2 x 103m2 pic3. 7 x 103m2 2. Suppose that an object travels from one point in space to another. Make a par between the displacement and the distance traveled. (Points 5) picThe displacement is either greater than or equal to the distance traveled. picThe displacement washbowl be either greater than, smaller than, or equal to the distance traveled. picThe displacement is always equal to the distance traveled. picThe displacement is either less than or equal to the distance traveled. 3. A grass moving horizontally to the right (+x direction) with a fixture of 500 m/s strikes a sandbag and penetrates a distance of 10. 0 cm. What is the reasonable 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 1 00 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) pic17 s pic4. 0 s pic0. 058 s pic0. 25 s 5.A bullet is fired horizontally, and at the homogeneous instant a second bullet is dropped from the same height. Ignore air resistance. Compare the times of fall of the two bullets. (Points 5) picThe fired bullet hits first. picThey hit at the same time. picThe dropped bullet hits first. piccannot tell without knowing the muckle 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) pic4. 0 N pic32 N pic16 N pic8. 0 N 7. A spring is characterized by a spring perpetual of 60 N/m. How much voltage energy does it store, when stretched by 1. cm? (Points 5) pic60 J pic600 J pic3. 0 x 10-3J pic0. 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) pic400 N pic40 N piczero pic800 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) pic42. 7 s pic27. 4 s pic47. s pic24. 7 s 10. A book weighs 6 N. When held at rest above your head the net force on the book is(Points 5) pic9. 8 N pic0 N pic6 N. pic-6 N. 11. 50 cm3of wood is floating on water, and 50 cm3of iron is totally submerged. Which has the greater buoyant force on it? Points 5) picthe iron picthe wood picBoth substantiate the same buoyant force. piccannot be determined without knowing their densities 12. In a hydraulic garage cite, 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 20,0 00 N on the large piston? (Points 5) pic5. 0 x 103N pic6. 7 x 103N pic2. 2 x 103N pic2. 9 x 103N 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) pic12. 5 Pa pic1. 25 kPa pic12. 5 kPa pic1. 5 Pa 14. A liquid has a specific gravity of 0. 357. What is its density? (Points 5) pic643 kg/m3 pic357 kg/m3 pic3570 kg/m3 pic1000 kg/m3 15.The frequency of a wave increases. What happens to the distance between successive crests if the speed remains constant? (Points 5) picIt increases. picIt decreases. picIt remains the same. picIt 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) pic4. m/s pic15 m/s pic36 m/s pic9. 0 m/s 17. An object in simple harmonic motion obeys the pursuit position versus time equation y = (0. 50 m) sin (? /2 t). What is the ampl itude of vibration? (Points 5) pic0. 0 m pic1. 0 m pic0. 25 m pic0. 75 m 18. On a day when the speed of sound in air is 340 m/s, a bat emits a shriek whose utter reaches it 0. 0250 s later. How far away was the object that reflected back the sound? Points 5) pic4. 25 m pic0. 850 m pic0. 425 m pic8. 50 m 19. A barking dog delivers around 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) pic68 dB pic61 dB pic65 dB pic63 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) pic8 Hz pic6 Hz pic5 Hz pic7 Hz