F 2 = 26 N.What third force will cause the object to be in equilibrium (acceleration equals zero)?

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1 FLEX Physical Science AP Physics C Mechanics - Midterm 1) If you set the cruise control of your car to a certain speed and take a turn, the speed of the car will remain the same. Is the car accelerating? A) Yes B) No 2) A fish weighing 16 N is weighed using two spring scales, each of negligible weight, as shown in the figure. What will be the readings of the scales? 1) 2) A) Each scale will read 8 N. B) The bottom scale will read 16 N, and the top scale will read zero. C) The scales will have different readings, but the sum of the two readings will be 16 N. D) Each scale will read 16 N. E) The top scale will read 16 N, and the bottom scale will read zero. 3) A child on a sled starts from rest at the top of a 15 slope. If the trip to the bottom takes 15.2 s how long is the slope? Assume that frictional forces may be neglected. A) 147 m B) 293 m C) 586 m D) 1130 m 4) The figure shows two forces acting on an object, with magnitudes F 1 = 78 N and F 2 = 26 N.What third force will cause the object to be in equilibrium (acceleration equals zero)? 3) 4) A) 52 N pointing up B) 82 N pointing down C) 82 N pointing up D) 52 N pointing down 1

2 5) Two blocks are connected by a string that goes over an ideal pulley as shown in the figure. Block A has a mass of 3.00 kg and can slide over a rough plane inclined 30.0 to the horizontal. The coefficient of kinetic friction between block A and the plane is Block B has a mass of 2.77 kg. What is the acceleration of the blocks? 5) A) 5.35 m/s2 B) 1.96 m/s2 C) 0.00 m/s2 D) 3.12 m/s2 E) m/s2 6) A roadway for stunt drivers is designed for racecars moving at a speed of 40 m/s. A curved section of the roadway is a circular arc of 230 m radius. The roadway is banked so that a vehicle can go around the curve with the friction force from the road equal to zero. At what angle is the roadway banked? A) 31 B) 33 C) 35 D) 29 E) 37 6) 2

3 7) Three objects are connected by massless wires over a massless frictionless pulley as shown in the figure. The tension in the wire connecting the 10.0-kg and 15.0-kg objects is measured to be 133 N. What is the mass M? 7) A) 35.0 kg B) 33.9 kg C) 95.0 kg D) 8.33 kg E) 52.8 kg 8) A 60.0-kg person rides in an elevator while standing on a scale. The scale reads 400 N. The acceleration of the elevator is closest to A) 6.67 m/s2 downward. B) 9.80 m/s2 downward. C) 6.67 m/s2 upward. D) 3.13 m/s2 downward. E) zero. 8) 3

4 9) Two boxes are connected by a weightless cord running over a very light frictionless pulley as shown in the figure. Box A, of mass 8.0 kg, is initially at rest on the top of the table. The coefficient of kinetic friction between box A and the table is Box B has a mass of 15.0 kg, and the system begins to move just after it is released. 9) (a) Draw the free-body diagrams for each of the boxes, identifying all of the forces acting on each one. (b) Calculate the acceleration of each box. (c) What is the tension in the cord? 10) A person is dragging a packing crate of mass 100 kg across a rough horizontal floor where the coefficient of kinetic friction is He exerts a force F sufficient to accelerate the crate forward. At what angle above horizontal should his pulling force be directed in order to achieve the maximum acceleration? A) 34.5 B) 30 C) 27.7 D) 21.8 E) 45 11) Engineers are designing a curved section of a highway. If the radius of curvature of the curve is 194 m, at what angle should the curve be banked so that a car traveling at 29.0 m/s will stay on the road without the aid of frictional forces? A) 26.1 B) 16.7 C) 21.0 D) ) A factory robot drops a 10 kg computer onto a conveyor belt running at 3.1 m/s. The materials are such that s = 0.50 and k = 0.30 between the belt and the computer. How far is the computer dragged before it is riding smoothly on the belt? A) 1.6 m B) 2.3 m C) 0.98 m D) 3.0 m 10) 11) 12) 4

5 13) The figure shows a graph of the acceleration of a 125-g object as a function of the net force acting on it. What is the acceleration at points A and B? 13) 14) You are standing in a moving bus, facing forward, and you suddenly fall forward as the bus comes to an immediate stop. The force acting on you that causes you to fall forward is A) the normal force due to your contact with the floor of the bus. B) the force due to kinetic friction between you and the floor of the bus. C) the force due to static friction between you and the floor of the bus. D) the force of gravity. E) No forces were acting on you to cause you to fall. 15) A dog is standing in the bed of a pickup truck. The bed is coated with ice, causing the force of friction between the dog and the truck to be zero. The truck is initially at rest, and then accelerates to the right, moving along a flat road. As seen from a stationary observer (watching the truck move to the right), the dog A) does not move left or right, but the back of the truck moves towards the dog. B) moves to the left, as the truck moves to the right, causing the dog to slide towards the back of the truck. C) moves to the right at the same rate as the truck, so it doesn't slide. D) moves to the right, but not as quickly as the truck is moving to the right, causing it to slide towards the back of the truck. 14) 15) 5

6 16) A stalled car is being pushed up a hill at constant velocity by three people. The net force on the car is A) up the hill and greater than the weight of the car. B) down the hill and greater than the weight of the car. C) zero. D) down the hill and equal to the weight of the car. E) up the hill and equal to the weight of the car. 17) In order to lift a bucket of concrete, you must pull up harder on the bucket than it pulls down on you. A) True B) False 18) A 20-ton truck collides with a 1500-lb car and causes a lot of damage to the car. During the collision A) the force on the truck due to the collision is slightly greater than the force on the car. B) the force on the car due to the collision is much greater than the force on the truck. C) the force of on the truck due to the collision is exactly equal to the force on the car. D) the car and the truck have the same magnitude acceleration. 19) Two forces act on a 55-kg object. One force has magnitude 65 N directed 59 clockwise from the positive x-axis, and the other has a magnitude 35 N at 32 clockwise from the positive y-axis. What is the magnitude of this object's acceleration? A) 1.7 m/s2 B) 1.3 m/s2 C) 1.5 m/s2 D) 1.1 m/s2 20) The figure shows a graph of the acceleration of an object as a function of the net force acting on it. The mass of this object, in grams, is closest to 16) 17) 18) 19) 20) A) B) 11. C) 130. D) 89. 6

7 21) A block lies on a horizontal frictionless surface. A horizontal force of 100 N is applied to the block giving rise to an acceleration of 3.0 m/s2. (a) Determine the mass of the block. (b) Calculate the distance the block will travel if the force is applied for 10 s. (c) Calculate the speed of the block after the force has been applied for 10 s. 21) 22) A monkey is sitting at the top of a tree 20 m above ground level. A person standing on the ground wants to feed the monkey. He uses a bow and arrow to launch the food to the monkey. If the person knows that the monkey is going to drop from the tree at the same instant that the person launches the food, how should the person aim the arrow containing the food? Air resistance is small enough to be ignored. A) He should aim it below the monkey. B) He should aim it above the monkey. C) He should aim it at the monkey. 22) 23) A child throws a ball with an initial speed of 8.00 m/s at an angle of 40.0 above the horizontal. The ball leaves her hand 1.00 m above the ground and experience negligible air resistance. (a) How far from where the child is standing does the ball hit the ground? (b) How long is the ball in flight before it hits the ground? 23) 24) An electron moves with a constant horizontal velocity of m/s and no initial vertical velocity as it enters a deflector inside a TV tube. The electron strikes the screen after traveling 17.0 cm horizontally and 40.0 cm vertically upward with no horizontal acceleration. What is the constant vertical acceleration provided by the deflector? (The effects of gravity can be ignored.) A) m/s2 B) m/s2 C) m/s2 D) m/s2 24) 25) The horizontal coordinates of a Frisbee TM in a strong wind are given by x = -12t + 4t 2 and y = 10t - 3t 2, where x and y are in meters, and t is in seconds. (a) What is the acceleration of the Frisbee? Give a magnitude and a direction, measuring angles from the positive x direction. (b) What is the magnitude of the velocity at t = 2.0 s, accurate to the nearest m/s? 25) 7

8 26) A catapult is tested by Roman legionnaires. They tabulate the results in a papyrus and 2000 years later the archaeological team reads (distances translated into modern units): Range = 0.20 km; angle of launch = /4; landing height = launch height. What is the initial velocity of launch of the boulders if air resistance is negligible? A) 0.69 m/s B) 22 m/s C) 1.4 m/s D) 44 m/s 27) A ball is thrown at a 60.0 angle above the horizontal across level ground. It is thrown from a height of 2.00 m above the ground with a speed of 20.0 m/s and experiences no appreciable air resistance. The time the ball remains in the air before striking the ground is closest to A) 3.32 s. B) 3.53 s. C) 3.64 s. D) 16.2 s. E) 3.07 s. 28) A plane flies directly between two cities, A and B, which are separated by 2300 mi. From A to B, the plane flies into a 65 mi/h headwind. On the return trip from B to A, the wind velocity is unchanged. The trip from B to A takes 65 min less than the trip from A to B. What is the airspeed of the plane, assuming it is the same in both directions? A) 610 mi/h B) 480 mi/h C) 530 mi/h D) 400 mi/h 29) Two particles, A and B, are in uniform circular motion about a common center. The acceleration of particle A is 8.5 times that of particle B. The period of particle B is 2.0 times the period of particle A. The ratio of the radius of the motion of particle A to that of particle B is closest to A) ra/rb = 2.1. B) ra/rb = 17. C) ra/rb = 4.3. D) ra/rb = E) ra/rb = ) A pilot drops a package from a plane flying horizontally at a constant speed. Neglecting air resistance, when the package hits the ground the horizontal location of the plane will A) depend of the speed of the plane when the package was released. B) be over the package. C) be behind the package. D) be in front of the package. 26) 27) 28) 29) 30) 8