Name: ______Class: ______Date: ______

Chapter 3 Projectile Motion, CP

Multiple Choice

Identify the letter of the choice that best completes the statement or answers the question.

_____1.A vector is a quantity that has

  1. magnitude and time.
  2. time and direction.
  3. magnitude and direction

______2.A scalar is a quantity that has

  1. direction.
  2. magnitude.
  3. time.
  4. color.

______3.When representing velocity as a vector,

  1. the direction of the arrow shows the direction of motion.
  2. the length of the arrow represents the speed.
  3. the length of the arrow is drawn to a suitable scale.
  4. all of the above
  5. none of the above

______4.In the absence of air friction, the horizontal component of a projectile’s velocity doesn’t change

as the projectile moves.

  1. Sometimes true
  2. Always true
  3. Always false

______5.An object is dropped and falls freely to the ground with an acceleration of g. It if is thrown

upward at an angle instead, its acceleration would be

  1. 0
  2. larger the g
  3. g upward
  4. g downward.
  5. none of the above

______6.A. cannonball is launched horizontally from a tower. If the cannon has a barrel velocity of

60 m/s, where will the cannonball be 1 second later? (Neglect air resistance.)

  1. 6 m downrange
  2. 30 m downrange
  3. 60 m downrange
  4. 300 m downrange
  5. none of the above

______7.What is the resultant of a 3-unit vector and 4-unit vector at right angles to each other?

  1. 1 unit
  2. 5 units
  3. 7 units.
  4. none of the above.

Name:______

______8.In the absence of air resistance, at what other angle will a thrown ball go the same distance as

one thrown at an angle of 75 degrees?

  1. 15 degrees.
  2. 65 degrees.
  3. 70 degrees.
  4. 80 degrees.
  5. 90 degrees.

Essay

9.Briefly distinguish between vectors and scalars, giving examples of each.

10.Figure 3.9 in the text shows two balls released simultaneously from a mechanism that

allows one ball to drop freely while the other is projected horizontally. Explain why

the balls fall farther and farther each successive time interval. Explain why the projected

ball has the same vertical location as the falling ball.

Problem

11.Quazimoto throws a ball horizontally from the top of a building that is 30 m high. He

hopes the ball will reach a swimming pool that is at the bottom of the building, 90 m

horizontally from the edge of the building. If the ball is to reach the pool, with what

initial speed must Quazimoto throw it with? (This is a two part problem, find the time,

then calculate the velocity) Show all work! Use knowns, unknowns, basic equations,

solutions and answers!

12.Consider an escalator at an angle of 45ᴼ above the horizontal that moves with a

velocity of 2 m/s. What is the horizontal component of the escalator’s velocity?

(usePythagorean formula, or if you choose, the trig function cos which is

adjacent/hypotenuse) Again, show all work!

13.A ball rolls off the edge of a horizontal roof at a velocity of 3 m/s. What is the

speed of the ball 3 seconds later? Show all work!

14.A ball is thrown upward. Its initial vertical component of velocity is 30 ms and its

initial horizontal component of velocity is 10 m/s. What is the ball’s speed

4 seconds later?

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