Part A (Using the Concepts): Multiple Choice: Identify the choice that best completes the statement or answers the question. Your choices are given below the text box. Make sure you include your strategy. 1. Four different students explain Newton's first law of motion in their own words. Which explanation is the best? a. If there is no net force on an object and the object is not moving, then the object will not start moving. If the object is moving with a constant velocity, then the velocity will not change. b. The acceleration of an object is proportional to the net force and inversely proportional to the object's mass. c. If the applied force is zero, then an object will not experience a change in motion. d. An object does not move unless a net force acts on it. 2. The forces acting on an object are 25 N [W] and 11 N [E]. The net force acting on the object is a. 36 N [W] b. 36 N [E] c. 14 N [W] d. 14 N [E] 3. (three marks) The forces acting on an object are 39 N [N], 13 N [S], and 12 N [S]. The net force acting on the object is a. 64 N [N] b. 40 N [N] c. 14 N [N] d. 14 N [S] 4. A customer at a hardware store pushes a trolley at a constant velocity across the floor with a horizontal force of 75 N [E]. The force of kinetic friction on the trolley is a. 75 N [E] b. 0N c. 75 N [W] d. cannot be determined without knowing the normal force and gravity 5. According to Newton's second law of motion, an object's acceleration is a. inversely proportional to the object's mass b. directly proportional to the net force C. in the direction of the net force d. all of the above 6. A crane pulls on a girder with a force of 2.5 kN [up] and gravity is 2.1 kN [down]. From this information we can conclude that the girder is a. speeding up b. moving up c. accelerating up d. all of the above 7. Which of the following statements is/are true about the units used to calculate the net force on an object? a. if the force is in N, then the mass is in kg and the acceleration is in m/s b. the force is in N and any units can be used for mass and acceleration c. the force, mass, and acceleration can be in any units d. all of the above 8. In an experiment, the acceleration of a 0.50-kg cart is 1.2 m/s [forward]. The net force acting on the cart is a. 0.60 N b. 2.4 N [forward] c. 0.60 N [forward] d. 2.4 N [backward] 9. The net force on a 1.2 x 103-kg car is 1.8 x 103 N [E]. The acceleration of the car is