KINS 382, LAB 10

1
KINS - 382, LAB 10

• Angular/Freefall/Projectile Review

2
1. Terms

• Angular distance The sum of all angular changes
  undergone by a rotating body (p.375-76).
• Angular displacement The change in the angular
  position or orientation of a line segment.
  (p.375-76).
• Radian Unit of angular measure used in
  angular-linear kinematic quantity conversions
  equal to 57.3. (p.376).
• Radius A line connecting the center of the
  circle to any point on the circumference of the
  circle. (p.341, previous edition).

3
Terms/Continued

• Angular velocity Rate of change in the angular
  position or orientation of a line segment.
  (p.378).
• Angular acceleration Rate of change in angular
  velocity. (p.380).

4
Question 2 /Answer 2

• Q. Write the formula for angular velocity.
  Isolate time. Isolate angles turned through.
• A. ? ? / t
• A. t ? / ?
• A. ? t (?)
• If you can not read these it is because there was
  a problem with the html conversion of the
  symbols. They are in your notes and the book.

5
Question 3 / Answer 3

• Q. Identify the four units that can be used for
  angular velocity.
• A.
  degrees/second (deg/s)
  radians/second (rad/s)
  revolutions/second (rev/s)
  revolutions/minute (rpm)

6
Question 4 / Answer 4

• Q. T or F In throwing events, the aerodynamic
  characteristics of the projected implements does
  not influence the trajectory.
• A. False, they do influence the outcome of the
  trajectory.

7
Question 5 / Answer 5

• Q. T or F Both halves of a parabola are
  symmetrical, therefore time to rise is equal to
  the time to fall.
• A. True

8
Question 6

• In a vacuum, a bullet is fired from a height of 1
  meter. At the same instant, a piece of chalk is
  dropped from a height of 1 meter.
• Based on your knowledge of vertical and
  horizontal components, which object will contact
  the Earth first?

9
Answer 6

• From Dr. Stulls lecture both will contact the
  ground at the same time if they are dropped from
  the same height.
• However, if the objects are not dropped in a
  vacuum then external forces (air resistance) will
  affect the flight of the chalk and bullet.

10
Question 7 / Answer 7

• Q. The ____________ components of projectile
  motion are influenced by gravity, whereas the
  ____________ component is not.
• A. vertical horizontal

11
Question 8 / Answer 8

• Q. T or F Once a body has been projected into
  the air, its overall (resultant) velocity is
  constantly changing because of the forces acting
  on it.
• A. True This example does not occur in a
  vacuum.

12
Question 9 / Answer 9

• Q. Horizontal motion relates to the ________ the
  projectile travels.
• A. distance

13
Question 10 / Answer 10

• Q. The vertical component relates to the maximum
  _________ height achieved by the projectile.
• A. height

14
Question 11 / Answer 11

• Q. A major factor that influences the vertical,
  but not the horizontal component of projectile
  motion is?
• A. a. direction
  b. gravity
  c. acceleration
  d.
  velocity

15
Question 12 / Answer 12

• Q. If an object were projected in a vacuum (with
  no air resistance), the horizontal component of
  its velocity would remain
• A. a. constant throughout the trajectory
  b. exactly the same
  c. constantly changing
  d. both a and b

16
Question 13 / Answer 13

• Q. Name the three factors that influence the
  trajectory of a projectile
• A. 1. angle of projection
  2. projection speed
  3. relative height

17
Question 14 / Answer 14

• Q. T or F For a body that is projected at an
  oblique angle, the speed of the projection
  determines both the height and horizontal length
  of the trajectory.
• A. True

18
Question 15 / Answer 15

• Q. In sporting events, to achieve maximum
  horizontal or vertical displacement of a
  projectile, the athletes primary goal is to
  maximize
• A. a. height of projection
  b. angle of projection
  c. speed of projection
  d. all of the above

19
Question 16 / Answer 16

• Q. T or F In most sporting events, the optimum
  angle of release is 25.
• A. False, 45 is the optimal angle of release
  for most projectiles.

20
Question 17 / Answer 17

• Q. T or F The horizontal acceleration of a
  projectile is always 0.
• A. True

21
Question 18 / Answer 18

• Q. T or F Performance in the performance of a
  vertical jump on a flat surface is entirely
  dependent on takeoff speed.
• A. False, Vertical jump performance is also
  dependant on the projection angle.The orientation
  of the body and the center of mass also affects
  the performance of a vertical jump.

22
Question 19 / Answer 19

• Q. A projectile is a body in free fall that is
  subject only to the forces of
• A. a. gravity
  b. air resistance
  c. acceleration
  d. a and b
  e. a, b and
  c

23
Question 20 / Answer 20

• Q. T or F With all other factors held
  constant, the greater the radius of rotation at
  which a swinging implement hits a ball, the
  greater the linear velocity imparted to the ball.
• A. True

24
Question 21

• Two baseballs are consecutively hit by a bat.
  The first ball is hit 20 cm. from the bats axis
  of rotation and the second ball is hit 40 cm from
  the bats axis or rotation.
• If the angular velocity of the bat was 30 rad/s
  at the instant that both balls were contacted,
  what was the linear velocity of the bat at the
  two contact points.

25
Answer 21

• r1 20 cm or .2 m, r2 40 cm or .4 m, ?
  30 rad/s
• Use V (r) ?
• V .20 m/rad (30 rad/s) 6m/s
• V .40 m/rad (30 rad/s) 12m/s

26
Question 22

• Green Bay attempts a field goal that is 29 m in
  length.
• If the ball was kicked with a horizontal
  component of initial velocity being 18 m/s and a
  flight time of 2 seconds.
• Was the kick long enough to make the field goal?

27
Answer 22

• Vh 18 m/s, t 2 s, dh ?
• Use dh Vh(t)
• dh 18 m/s (2s)
• dh 36 m
• The kick was long enough!