Phys 111 Exam 1 September 22, 2015 1. The time T required for one complete oscillation of a mass m on a spring of force constant k is T = 2π m k. Find the dimension of k to be dimensionally correct for this equation. A) [L] [T] B) [M] [T] 2 [T]2 C) [M] D) [L] [T] 2 [M] E) [L] 2. Suppose that an object travels from one point in space to another. Make a comparison between the displacement and the distance traveled. A) The displacement is either greater than or equal to the distance traveled. B) The displacement is always equal to the distance traveled. C) The displacement is either less than or equal to the distance traveled. D) The displacement can be either greater than, smaller than, or equal to the distance traveled. E) If the displacement is equal to zero, then the distance traveled will be also equal to zero. 3. You drop a stone from a bridge to the river below. After this stone has traveled a distance d, you drop a second stone. The distance between the two stones will always A) increases. B) decreases. C) stays constant. D) increases at first, but then stays constant. E) decreases at first, but then stays constant. 4. A car traveling with velocity v is decelerated by a constant acceleration of magnitude a. It travels a distance d before coming to rest. If its initial velocity were increased by a factor of two, the distance required to stop would A) double. B) decrease by a factor of two. C) stay the same. D) quadruple. E) decrease by a factor of four. 5. A car is making a 12-mile trip. It travels the first 6.0 miles at 30 miles per hour and the last 6.0 miles at 60 miles per hour. What is the car's average speed for the entire trip? A) 20 mph B) 35 mph C) 40 mph D) 45 mph E) 50 mph 6. From the graph below, which plots the distance d versus time with a constant acceleration, find the magnitude of the acceleration in units of m/s 2? 1
A) 0 m/s 2 B) 2 m/s 2 C) 4 m/s 2 D) 10 m/s 2 E) 20 m/s 2 7. A ball with mass m = 1 kg is thrown in the trajectory shown in the figure below with initial velocities V 0x = 30 m/s and V 0y = 40 m/s in the x- and y-axis respectively. (Use g =10 m/s 2 ). B V 0y = 40 m/s V 0x =30 m/s How long it will take for the ball to reach the highest point, B? A) 2 s B) 3 s C) 4 s D) 5 s E) 6 s 8. Using the figure above that the ball is thrown in the trajectory, calculate the range R, in meters, shown in the figure (Use g =10 m/s 2 ). A) 30 m B) 120 m C) 150 m D) 200 m E) 240 m 9. Vector M = 4.00 m points eastward and vector N = 3.00 m points southward. The resultant vector M + N is given by A) 5.00 m at an angle 36.9 south of east. 2
B) 5.00 m at an angle 53.1 south of east. C) 5.00 m at an angle 71.6 south of east. D) 5.00 m at an angle 18.4 south of east. E) 5.00 m at an angle 26.6 south of east. 10. You are adding vectors of length of 20 and 40 units. What is the possible resultant magnitude that you can obtain out of the following choices? A) 0 units B) 18 units C) 37 units D) 64 units E) 100 units 11. An astronaut stands by the rim of a crater on the moon, where the acceleration of gravity is 1.62 m/s 2. 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 time is 6.3 s, what is the depth of the crater? A) 26 m B) 32 m C) 14 m D) 10 m E) 38 m 12. A swimmer heading directly across a river reaches the opposite bank in 6 min 40 s. She is swept downstream 480 m. What is the speed of the current? A) 1.4 m/s B) 0.50 m/s C) 0.80 m/s D) 1.2 m/s E) 1.8 m/s 13. You are throwing a ball straight up in the air. At the highest point, the ball s A) Velocity and acceleration are zero B) Velocity is nonzero but its acceleration is zero C) Velocity is zero but its acceleration is nonzero D) Velocity and acceleration are both nonzero E) None of the above statements is true 14. If you double the mass of the earth and the mass of the sun is the same then reduce the distance between the earth and the sun by a factor of 2, how do the force of gravity exerted on the earth by the sun change? A) Increases by a factor of 2 B) Increases by a factor of 4 C) Increases by a factor of 8 D) Increases by a factor of 16 E) Increases by a factor of 32 15. A 50.0-kg box is being pushed along a horizontal surface. The coefficient of kinetic friction between the box and the ground is 0.350. What horizontal force must be exerted on the box for it to accelerate at 1.20 m/s 2? (use g = 9.81 m/s 2 ) 3
A) 232 N B) 60.0 N C) 491 N D) 116 N E) 172 N 16. The two forces indicated in Figure below act on a 3.00-kg object. What is the acceleration of the object? A) (1.67 m/s2) ˆx - (0.333 m/s2) ŷ B) (5.00 m/s2) ˆx + (1.00 m/s2) ŷ C) (1.67 m/s2) ˆx + (2.333 m/s2) ŷ D) (15.0 m/s2) ˆx + (3.00 m/s2) ŷ E) (1.67 m/s2) ˆx + (0.333 m/s2) ŷ 17. A hockey puck slides on ice at constant velocity. What is the net force acting on the puck? A) more than its weight B) equal to its weight C) less than its weight but more than zero D) depends on the speed of the puck E) zero 18. A 60.0-kg person steps on a scale in an elevator. The scale reads 708 N. What is the magnitude of the acceleration of the elevator? (use g = 9.81 m/s 2 ). A) +0.00 m/s 2 B) +2.00 m/s 2 (elevator upward) C) - 2.00 m/s 2 (elevator downward) D) +4.00 m/s 2 (elevator upward) E) - 4.00 m/s 2 (elevator downward) 4
19. A m 1 =2.00-kg mass and a m 2 =5.00-kg mass hang vertically at the ends of a rope that goes over an ideal pulley. If the masses are released, what is the resulting acceleration of the masses? (g=9.81 m/s 2 ). A) 0 m/s 2 B) 7.01 m/s 2 C) 4.20 m/s 2 D) 3.68 m/s 2 E) 2.80 m/s 2 20. A locomotive is pulling three wagons along a level track with a force of F=100,000 N. The wagon next to the locomotive has a mass of m 1 =80,000 kg, the next one, m 2 =50,000 kg, and the last one, m 3 =70,000 kg. Neglect friction. What is the force between the 80,000-kg and 50,000-kg wagons? F m 1 m 2 m 3 A) 35,000 N B) 40,000 N C) 50,000 N D) 60,000 N E) 65,000 N 5