Use the following information for the remaining multiple-choice questions: When
ID: 1332959 • Letter: U
Question
Use the following information for the remaining multiple-choice questions:
When an object with mass m is dropped near the surface of Earth, it will fall to the ground due to the force of gravity. Near the surface the force of gravity, F, can be determined from the following equation: F = m g where g is the acceleration due to gravity (g = 9.8 m/s2 ). In the presence of air, a falling object will also experience an air resistance, Fa, which opposes the motion of the object. The net force on an object with mass m falling through the air near the surface of Earth is thus given by: Fnet = m g - Fa The air resistance, Fa, depends on such factors as the speed, size, shape, and surface texture of the object.
16. To conduct an experiment, a scientist has two metal spheres made to have the same diameter and surface texture. Sphere A is hollow and has a mass of m, while sphere B is solid and has a mass of 4m. The scientist drops the two spheres at the same time from a tall structure. As the two spheres fall through the air, which sphere has the greater acceleration after 1 second? A) Sphere A. B) Sphere B C) They have the same acceleration. D) There is not enough information to tell.
17. The two spheres fall to the ground below. Which of the following is true? A) Sphere A will land first because it experiences less air resistance. B) Sphere B will land first because it experiences less air resistance. C) Sphere B will land first because it has the largest weight, and the least effect of the air resistance. D) They will land at the same time, because all objects fall with the same acceleration.
18. In another experiment, the scientist drops an object from a high-flying balloon. The object reaches terminal velocity after 8 seconds. During which time interval does it travel the greatest distance? A) 0-1s B) 2-3 s C) 4-5 s D) 6-7 s
19. Consider again the object dropped from a high-flying balloon and reaching terminal velocity after 8 seconds. During which time interval does it increase its velocity by the greatest amount? A) 0-1s B) 2-3 s C) 4-5 s D) 6-7 s
20. The scientist wants to investigate the effect of size and surface texture on the air resistance. She designs an experiment using a smooth sphere with a small diameter, a rough sphere with a small diameter, and smooth sphere with a larger diameter. Which sphere is her control? A) The smooth sphere with the small diameter B) The rough sphere with the small diameter C) The smooth sphere with the larger diameter D) Neither. The experiment is not controlled.
Explanation / Answer
(16) acceleration a=g - (Fa/mass). this greater for greater mass that is for solid sphere. option (B) is correct answer.
(17) option (C) is correct answer.
(18)
distance travelled in nth second is given by,
Sn=v0+a(n-1/2)
so, the option (D) is correct answer.
(19)
the expression for final velocity is,
v=v0+at
the increase in velocity by greatest amount during the time interval 6-7 s.
(20)
option (C) is correct.