← All sample quizzes

Sample Quiz: Physics Chapter 1

Concepts of Motion — Physics for Scientists and Engineers: A Strategic Approach (Randall D. Knight)

10 questions · 23 points · answer key included

Download the Word file

No account, no email — the file downloads straight away.

Multiple Choice

  1. ApplyA spaceship descending to Mars slows down as it approaches the surface. Based on the motion diagram principle, which statement correctly describes the relationship between the velocity and acceleration vectors during this descent? (2 PTS)
    1. The acceleration vector is zero because the spaceship's speed is decreasing.
    2. The velocity and acceleration vectors point in the same direction because the spaceship is moving downward.
    3. The velocity vector points downward while the acceleration vector points upward, but they are unrelated.
    4. The velocity and acceleration vectors point in opposite directions because the spaceship is slowing down.
  2. ApplyA skier glides along horizontal snow at constant speed, then accelerates down a hill. In a motion diagram of this motion, how would the spacing of the dots differ between the horizontal section and the downhill section? (2 PTS)
    1. The dots are closer together on the horizontal section and farther apart on the downhill section.
    2. The dot spacing cannot be determined without knowing the exact slope angle.
    3. The dots are equally spaced throughout because the skier maintains constant speed.
    4. The dots are farther apart on the horizontal section and closer together on the downhill section.
  3. ApplyA ball is tossed straight up into the air. At the highest point of its trajectory, which of the following is true about the ball's acceleration? (2 PTS)
    1. The acceleration points upward to oppose the downward pull of gravity.
    2. The acceleration is zero because the velocity is momentarily zero at the top.
    3. The acceleration points downward, the same direction as it does while the ball is falling.
    4. The acceleration changes direction from upward to downward at the highest point.
  4. ApplyAn Audi TT accelerates from 0 to 60 mph in 6 seconds. Using the definition of average acceleration, which expression correctly represents the average acceleration during this interval? (2 PTS)
    1. vecaavg = 60 mph × 6 s
    2. vecaavg = ΔvecvΔ t = (60 mph - 0 mph)/(6 s)
    3. vecaavg = (60 mph)/(6 s)
    4. vecaavg = distance/time = (60 mph)/(6 s)
  5. ApplyIn a motion diagram, the acceleration vector at a particular point is determined by examining the velocity vectors before and after that point. What does the direction of the acceleration vector indicate? (2 PTS)
    1. The direction the object will move in the next time interval.
    2. The direction opposite to the object's motion.
    3. The direction of the change in velocity, Δvecv.
    4. The direction the object is currently moving.

True or False

  1. In a motion diagram, equally spaced dots indicate that an object is moving with constant speed. (1 PTS)
  2. When an object is slowing down along a straight line, the velocity and acceleration vectors point in the same direction. (1 PTS)
  3. The sign of the acceleration vector indicates whether an object is speeding up or slowing down. (1 PTS)

Problem Solving

  1. A tricycle in Manila accelerates from rest and travels along a straight road. The motion diagram shows displacement vectors of lengths 0.5 m, 1.0 m, 1.5 m, and 2.0 m for successive time intervals of 1 second each. (a) Is the tricycle speeding up or slowing down? (b) Describe how you can tell from the displacement vectors. (5 PTS)
  2. A jeepney traveling down a hill applies its brakes and comes to a stop. Draw a complete motion diagram for the last 5 seconds of the jeepney's motion, showing: (a) at least five position dots, (b) displacement vectors labeled Δ vecrn, and (c) velocity vectors labeled vecv. Explain how your diagram shows that the jeepney is slowing down. (5 PTS)

Answer key

Multiple Choice

  1. 1.D — According to the principle stated in the textbook, when an object is slowing down, the acceleration and velocity vectors point in opposite directions; the spaceship moving downward (velocity down) while decelerating means acceleration points upward.
  2. 2.A — In a motion diagram, equally spaced dots indicate constant speed, while increasing spacing indicates speeding up; the skier moves at constant speed horizontally (equal spacing) then speeds up downhill (increasing spacing).
  3. 3.C — Even though velocity is zero at the top, the acceleration is not zero; the acceleration points downward throughout the motion, including at the top, because the velocity is changing from upward to downward.
  4. 4.B — Average acceleration is defined as vecaavg = ΔvecvΔ t, the change in velocity divided by the time interval; this correctly shows the change from 0 to 60 mph over 6 seconds.
  5. 5.C — The acceleration vector points in the same direction as Δvecv, the change in velocity; it is found by determining what vector must be added to the earlier velocity to obtain the later velocity.

True or False

  1. 1.True — The textbook principle states that images that are equally spaced indicate an object moving with constant speed, which is directly shown in motion diagrams where displacement vectors of equal length represent constant velocity.
  2. 2.False — According to the textbook principle on linear acceleration, when an object is slowing down, the acceleration and velocity vectors point in opposite directions, not the same direction.
  3. 3.False — The textbook explicitly states that the sign of acceleration tells us which way the acceleration vector points, not whether the object is speeding up or slowing down. Whether an object speeds up or slows down depends on the relative directions of velocity and acceleration vectors.

Problem Solving

  1. 1.(a) The tricycle is speeding up. (b) The displacement vectors are increasing in length with each successive time interval. According to the textbook principle, an object is speeding up if its displacement vectors are increasing in length. — The problem tests understanding of how displacement vectors in a motion diagram indicate changes in speed. Increasing displacement vector lengths directly indicate acceleration (speeding up), as stated in the textbook section on motion diagrams with displacement vectors.
  2. 2.The motion diagram should show: (a) Five or six dots getting progressively closer together as the jeepney approaches the stop point, with the final dot labeled "Stop"; (b) Displacement vectors connecting consecutive dots, with each successive vector shorter than the previous one; (c) Velocity vectors of decreasing length. The diagram shows slowing down because the displacement vectors (and velocity vectors) are decreasing in length, indicating that the distance traveled in each equal time interval is becoming smaller. — This problem requires students to construct a complete motion diagram following the textbook procedure for motion diagrams with displacement vectors, demonstrating understanding that decreasing displacement vector lengths indicate deceleration.