A box of mass 0.50 kg slides down a rough ramp with an initial speed of 2.0 m/s. The ramp is inclined at an angle of 30' above the horizontal. The box slides a distance of 1.5 m and comes to rest before reaching the bottom of the ramp. The energy dissipated as the box slides to a stop is most nearly (A) 0 (B) 1.4J (C) 2.8J (D) 4.7J (E) 8.4.] A 20 kg box moving at an initial speed of 10 m/s slides 25 m to the right on a horizontal oor before it comes to a complete stop. 9. What is the coefcient of friction between the box and the floor? (A) 0.10 (B) 0.20 (C) 0.40 (D) 0.60 (E) 0.80 Figure 1 Figure 2 The students now move the block to a ramp that is identical to the rst one except that it has a rough surface. Figure 1 shows the block as it is sliding down the ramp. Figure 2 shows a free-body diagram for the block when it is at the moment shown in Figure 1. Which of the following claims is supported by the gures? (A) Earth's gravitational force does less work on the block when it is on the rst ramp with the rough surface. (B) Earth's gravitational force does more work on the block when it is on the rst ramp with the rough surface. (C) Friction does negative work on the block. (D) Friction does positive work on the block. (E) The normal force does positive work on the block. Force Sensor Cart Motion Sensor .1- teacher does a demonstration in front of a class. For the demonstration, a motion sensor is placed at the end of a long, horizontal track of negligible friction. A force sensor is used to pull a cart of known mass along the track, and the motion sensor tracks the motion of the cart. For several positions of the cart, a computer records the reading on the force sensor and the reading on the motion sensor for both the speed of the cart and the distance the cart moves away from the motion sensor. Based on only these data, which of the following scientic hypotheses could a student test? (A) The force exerted on the cart is directly proportional to the time the can has moved. (B) The gravitational acceleration for an object on Earth is constant near Earth's surface. (C) The net work done on the cart is equal to the change in kinetic energy of the cart. (D) As the force the sensor exerts on the cart increases, so does the acceleration of the cart. (E) Earth's gravitational force is a conservative force. 6. Several identical objects are initially at rest on a horizontal surface. The following gures are free-body diagrams for the forces that are exerted on the objects over a distance Ax. In which of the diagrams is the net work being done on the object zero? (A) (B) (C) (D (E) All four free-body diagrams shown show a net force that would do work on the object. 7. P - X A particle P is located on the x-axis, as shown in the figure. A force exerted on the particle is given by the equation F = kx', where k = 4-5. How much work is done by the force in moving the particle from z = 2 m to x = 1m? (A) 15 J 28 J 32 J (D) 36 J (E) 60 J