Chapter 2 Conceptual Practice

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Chapter 2 Conceptual Practice

• 1) As an object falls downward, its
• A) velocity increases
• B) acceleration increases
• C) Both of these.
• D) None of these.

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Chapter 2 Conceptual Practice

• 2)Whirl a rock at the end of a string on an
  ice-covered pond and it follows a circular path.
  If the string breaks, the tendency of the rock is
  to
• A) continue to follow a circular path.
• B) follow a straight-line path.
• C) increase its speed.
• D) revolve in a smaller circle.

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Chapter 2 Conceptual Practice

• 3) A sheet of paper can be withdrawn from under
  a container of milk without toppling it if the
  paper is jerked quickly. This best demonstrates
  that
• the milk carton has no acceleration.
• there is an action-reaction pair of forces.
• gravity tends to hold the milk carton secure.
• the milk carton has inertia.
• None of these.

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Chapter 2 Conceptual Practice

• 4) The gain in speed each second for a
  freely-falling object is about
• 0
• 5 m/s
• 10 m/s
• 20 m/s
• Depends on the initial speed.

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Chapter 2 Conceptual Practice

• 5) A package fall off a truck that is moving at
  30 m/s. Neglecting air resistance, the horizontal
  speed of the package just before it hits the
  ground is
• zero.
• less than 30 m/s but larger than zero.
• 30 m/s.
• more than 30 m/s.
• More info needed for an estimate.

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Chapter 2 Conceptual Practice

• 6) A truck is moving at constant velocity.
  Inside the storage compartment, a rock is dropped
  from the midpoint of the ceiling and strikes the
  floor below. The rock hits the floor
• exactly below the midpoint of the ceiling.
• ahead of the midpoint of the ceiling.
• behind the midpoint of the ceiling.
• More info needed to solve this problem.
• None of these.

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Chapter 2 Conceptual Practice

• 7) If your automobile runs out of fuel while you
  are driving the engine stops but you do not come
  to an abrupt stop. The concept that most explains
  why is
• inertia.
• gravity.
• acceleration.
• resistance.

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Chapter 2 Conceptual Practice

• 8) According to Newtons law of inertia, a
  railroad train in motion should continue going
  forever even if its engine is turned off. We
  never observe this because railroad trains
• move too slowly.
• are much too heavy.
• must go up and down hills.
• always have forces that oppose their motion.

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Chapter 2 Conceptual Practice

• 9) Immediately after a rocket ship accelerating
  in outer space runs out of fuel it
• accelerates for a short time, then slows down to
  a constant velocity.
• accelerates for a short time, slows down, and
  eventually stops.
• no longer accelerates.

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Chapter 2 Conceptual Practice

• 10) If no external forces are acting on a moving
  object it will
• continue moving at the same speed.
• continue moving at the same velocity.
• move slower and slower until it finally stops.

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Chapter 2 Conceptual Practice

• 11) The last instant just before an airplane
  crashes a passenger jumps out the door and falls
  only two feet to the ground. The passenger is
• probably hurt or killed.
• unharmed.
• intelligent to think so fast.
• lucky to have studied physics.

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Chapter 2 Conceptual Practice

• 12) A scientific statement that can never be
  changed is a scientific
• theory.
• principle.
• hypothesis.
• law.
• None of the above choices are correct.

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Chapter 2 Conceptual Practice

• 13) A girl and a boy pull in opposite directions
  on strings attached to each end of a spring
  balance. Each child exerts a force of 20N. What
  will the reading on the spring balance be?
• 0 N
• 10 N
• 20 N
• 40 N

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Chapter 2 Conceptual Practice

• A person standing on a scaffold lowers an object
  of weight 250N by means of a rope, at constant
  speed. If the weight of the rope is negligible,
  the force that the person exerts is
• constant and less than 250N
• equal to 250N
• less than 250N and decreasing
• greater than 250N

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Chapter 2 Conceptual Practice

• A passenger not wearing a safety belt hits the
  windscreen of a car in a head-on collision. This
  is an illustration of
• Newton's First Law
• Newton's Second Law
• the Law of Conservation of Momentum
• Newton's Universal Law of Gravitation