Effects of forces on speed and direction Transitional Reasoning Practice

Questions

1. 1.

   An autonomous surface vessel navigates a calm lake at a steady speed of 4 m/s heading due north. To avoid an obstacle, the guidance system executes two consecutive maneuvers: first, it changes its heading toward the northwest while keeping its speed constant at 4 m/s; second, it proceeds along that new straight path while steadily decreasing its speed to 2 m/s. Which statement correctly identifies the required direction of the net horizontal force relative to the vessel's direction of motion during each maneuver?

   • A) Maneuver 1 requires a net force directed backward at an acute angle to the direction of motion, and Maneuver 2 requires a net force directed perpendicular to the path.
   • B) Maneuver 1 requires a net force directed forward along the direction of motion, and Maneuver 2 requires a net force directed perpendicular to the path.
   • C) Maneuver 1 requires a net force directed perpendicular to the instantaneous direction of motion, and Maneuver 2 requires a net force directed opposite to the direction of motion.
   • D) Maneuver 1 requires a net force directed perpendicular to the instantaneous direction of motion, and Maneuver 2 requires a net force directed forward along the direction of motion.
2. 2.

   An automated research cart travels forward along a straight, level track at a steady speed. A mounted propulsion unit is activated, exerting a continuous, constant horizontal force directed straight backward along the track. The cart slows down, comes to a momentary stop, and continues to move under the influence of this same force. Which statement correctly describes the cart's speed and direction of motion before and after it momentarily stops?

   • A) Before stopping, its speed decreases while moving forward; after stopping, its speed increases while moving backward.
   • B) Before stopping, its speed decreases while moving forward; after stopping, it remains at rest because the backward force cannot cause motion.
   • C) Before stopping, its speed decreases while moving backward; after stopping, its speed increases while moving forward.
   • D) Before stopping, its speed remains constant while moving forward; after stopping, its speed increases while moving backward.
3. 3.

   A test car travels along a curved, horizontal track. As the car rounds the bend, the driver presses the accelerator so that the car simultaneously continues turning along the curve and increases its speed. Based on the effects of forces on motion, which statement correctly describes the direction of the net horizontal force acting on the car during this maneuver?

   • A) It points at an acute angle forward and toward the inside of the curve, combining a forward component that increases speed and an inward component that changes direction.
   • B) It points strictly perpendicular to the direction of motion toward the inside of the curve, because following a curved path requires only a centripetal force.
   • C) It points strictly along the forward line of motion, because an increase in speed requires the entire net force to align with the direction of travel.
   • D) It points at an obtuse angle backward and toward the outside of the curve, because acceleration creates an opposing inertial force away from the turn.
4. 4.

   An autonomous drone flies horizontally across a test arena in three consecutive flight segments: in Segment 1, it travels in a straight line while steadily speeding up; in Segment 2, it rounds a curve at a steady speed of 10 m/s; and in Segment 3, it continues along a straight line at a constant speed of 10 m/s. Based on the effects of forces on motion, which statement correctly identifies the net horizontal force acting on the drone during each segment?

   • A) In Segment 1, the net force acts in the direction of motion; in Segment 2, it acts perpendicular to the motion; in Segment 3, the net force is zero.
   • B) In Segment 1, the net force acts perpendicular to the motion; in Segment 2, it acts in the direction of motion; in Segment 3, the net force acts opposite to the motion.
   • C) In Segment 1, the net force acts in the direction of motion; in Segment 2, the net force is zero; in Segment 3, it acts perpendicular to the motion.
   • D) In Segment 1, the net force acts opposite to the motion; in Segment 2, it acts in the direction of motion; in Segment 3, the net force is zero.
5. 5.

   A solar-powered exploratory rover travels straight north at a steady speed across a level test field. To evaluate its braking system, the control unit simultaneously activates two horizontal thrusters: Thruster X exerts a constant 50 N force directed south, while Thruster Y exerts a constant 20 N force directed north. If all other horizontal resistive forces are negligible, how does this combined thruster action initially affect the speed and direction of the rover?

   • A) The rover's speed increases, and its direction of motion deflects toward the east.
   • B) The rover's speed decreases, and its direction of motion curves toward the south.
   • C) The rover's speed decreases, and its direction of motion remains straight toward the north.
   • D) The rover's speed remains constant, and its direction of motion instantly reverses toward the south.
6. 6.

   A deep-space research probe is coasting at a constant velocity far from any gravitational influences. Mission controllers fire a continuous maneuvering thruster that exerts a constant net force oriented at an angle of 135° relative to the probe's forward direction of travel. Which statement correctly describes the initial effect of this force on the probe's speed and direction of motion?

   • A) Its speed decreases while its direction of motion curves toward the line of the applied force.
   • B) Its speed increases while its direction of motion continues along its original straight path.
   • C) Its speed remains constant while its direction of motion immediately reverses along the same axis.
   • D) Its speed decreases while its direction of motion remains strictly along its initial straight heading.
7. 7.

   An automated laboratory puck glides east at a constant speed across a frictionless horizontal air table. As it passes a marker, an internal blower turns on, applying a continuous, constant horizontal force directed toward the north. Which statement correctly describes the resulting motion of the puck?

   • A) The puck immediately changes direction to travel due north at its original speed.
   • B) The puck follows a curved path toward the northeast while its overall speed increases.
   • C) The puck travels along a straight diagonal line toward the northeast at a constant speed.
   • D) The puck curves toward the north while its overall speed continuously decreases.

Answers and step-by-step solutions appear after you finish the test.