tailieunhanh - Makeup Exam #1
M1) Assuming that it takes s for the driver to react before applying the brakes, what is the stopping distance (the distance from the point where the driver first sees the need to stop to the point where the car comes to a stop) for a car traveling at 25 m/s if the deceleration due to the brakes is m/s2? A) 174 m B) 87 m C) 186 m D) 92 m 2) An astronaut stands by the rim of a crater on the moon, where the acceleration of gravity is m/s2. To determine the depth of the crater, she drops a rock and measures. | Makeup Exam #1 Name: MULTIPLE CHOICE. Choose the one alternative that best completes the statement or answers the question. 1) Assuming that it takes s for the driver to react before applying the brakes, what is the stopping distance (the distance from the point where the driver first sees the need to stop to the point where the car comes to a stop) for a car traveling at 25 m/s if the deceleration due to the brakes is m/s2? A) 174 m B) 87 m C) 186 m D) 92 m 2) An astronaut stands by the rim of a crater on the moon, where the acceleration of gravity is m/s2. To determine the depth of the crater, she drops a rock and measures the time it takes for it to hit the bottom. If the depth of the crater is 120 m, how long does it take for the rock to fall? A) s B) s C) s D) s 3) A projectile is launched with an initial velocity of 80 m/s at an angle of 30e above the horizontal. Neglecting air resistance, what is horizontal component of the projectile's acceleration? A) 80 m/s2 B) m/s2 C) 0 m/s2 D) m/s2 4) A boy kicks a football with an initial velocity of m/s at an angle of above the horizontal. What is the highest elevation reached by the football in its trajectory? A) m B) m C) m D) m 1 5) A net force of 120 N is applied to a certain object. As a result, the object accelerates with an acceleration of m/s2. The mass of the object is A) kg. B) kg. C) 2880 kg. D) 144 kg. 6) A locomotive is pulling three wagons along a level track with a force of 100,000 N. The wagon next to the locomotive has a mass of 80,000 kg, the next one, 50,000 kg, and the last one, 70,000 kg. Neglect friction. What is the force between the 50,000-kg and 70,000-kg wagons? A) 35,000 N B) 65,000 N C) 40,000 N D) 60,000 N 7) In the figure below, the block of mass m is at rest on an inclined plane that makes an angle q with the horizontal. The force of static friction f must be such that A) f > mg. B) f = mg sinq. C) f
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