1. A pitcher throws a fastball. After the ball has left the pitcher's hand and is moving through the air, which forces are acting on the baseball? 3) the force from the throw and the downward force of gravity . b) the force from the throw, a force exerted by the air, and the downward force of gravity. c) a force exerted by the air and a force from the throw. d) a force exerted by the air and downward force of gravity. 2. A person with a mass of 62 kg is an elevator moving at a constant velocity of 2.3 m/s [up]. What is the magnitude of the net force acting on the person? a) 0 N c) 620 N b) 610 N d)6100N 3. When the net force acting on an object is doubled, the effect on the acceleration of the object will be a) tripled c) quartered b) doubled d) constant 4. A force of 9.0 N exerted by a rope pulls a block with a mass of 4.5 kg. The block is resting on a smooth surface. What is the force of reaction exerted by the block on the rope? a) 4.5 N c) 41 N b) 9.0 N d) 44 N 5. An object is suspended from a spring balance in an elevator. The reading is 240 N when the elevator is at rest. The spring balance reading changes to 220 N. Which of the following describes how the elevator is moving? a) downward with constant speed. c) downward with increasing speed. b) downward with decreasing speed. d) upward with increasing speed. 6. A child with a mass m is sliding down a slide that is inclined at an angle 9 above the horizontal. The magnitude of the normal force on the child is a) my tan 6 c) mg cos 9 b) my sin 6 d) mg