# CP Ch3 Projectile Motion

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```					Mr. C’s Physics: Vectors and Projectiles Review & Study Guide                                              Page 1 of 3
1. What do scalars and vectors have in common? ___________________ What do vectors have that
scalars do not have? ___________________

2. Name at least 4 scalars____________________________________________________________________

3. Name at least 3 vectors ___________________________________________________________________

4. Use the graph to the right. Each division (on the X and Y) is 6m, and
up is north. Label the graph with this information.

5. Draw a vector that is not along the X or Y axis. Find its components and
direction using graphical methods only.

6. If you have a vector but no graph paper, ruler, or protractor how do you find
the opposite side’s component? ______________ Adj.?_______________

7. If we have several vectors to add, why do we often find their components first?
______________________________________________________________________________________

8. If you know both components of a vector, how do you find the resultant (hypotenuse)? ________________
______________________________________________________________________________________

9. If you are traveling at a velocity of 20m/s 30° north of west, what is your north component? ____________
East component? (Yes, there is an east component  ) __________________________________________

10. After a rock that is thrown straight up reaches the top of its path and is starting to fall back down,
its acceleration is (neglecting air resistance) __________.

11. When representing velocity as a vector __________. A) the direction of the arrow shows the
direction of motion. B) the length of the arrow is drawn to a suitable scale. C) the length of the
arrow represents the speed. D) all of the above E) none of the above
12. Jose can jump vertically 1 meter from his skateboard when it is at rest. When the skateboard is
moving horizontally, Jose can jump __________.

13. A ball is thrown into the air at some angle. At the very top of the ball's path, its velocity is______.

14. At the instant a ball is thrown horizontally with a large force, an identical ball is dropped from e
same height. Which ball hits the ground first? _________________________________________________

15. How does the velocity change in the horizontal? _______________________________________________
In the vertical? _________________________________________________________________________

16. An airplane flying into a head wind loses ground speed, and an airplane flying with the wind
gains ground speed. If an airplane flies at right angles to the wind, then ground speed is ________________
17. A cannonball is launched from the ground at an angle of 30 degrees above the horizontal and a
speed of 20 m/s. Ideally (no air resistance) the ball will land on the ground with a speed of _____________
Mr. C’s Physics: Vectors and Projectiles Review & Study Guide                                             Page 2 of 3
18. A marble is shot from ground level with an initial horz. vel. of 20m/s, and       Horz v     Vert v       time
an initial vert. vel of 30m/s. Approximate g ≈ 10m/s2 Fill in the table for       (      )   (      )     (      )
each second until the marble strikes the ground again. Put proper units in
the table’s header. Hint: the vert. vel. is NOT 30m/s at 1s.

Horz d     Vert d     time        19. Using the information above, fill in the
(      )   (      )   (      )
horz. and vert. displacements until the
marble strikes the ground.

20. Ball A is thrown at 20 degrees above the ground. Ball B is
identical and is thrown at 70 degrees above the ground. Which
hits the round first?______________ Which lands further away?
________________

21. In the absence of air resistance, the angle at which a thrown ball will go the farthest is _________________
22. In the absence of air friction, the vertical component of a projectile's velocity doesn't change as
the projectile moves. A) Always false B) Sometimes true C) Always true

23. Suppose a small plane can fly at 200 km/h relative to the surrounding air. Suppose also that there
is a 40-km/h tailwind. How fast does the plane's shadow move across the ground? ____________________
24. If it turns around and flies into the wind, how
fast does the plane's shadow move across the ground? ___________________________________________
25. A projectile is fired horizontally in a vacuum. The projectile maintains its horizontal component
of speed because ________________________________________________________________________

26. You go 55m at 36.87° west of north and then, you
then travel 88m at 30° south of east. What is your
displacement from your original point? It might help
to draw out a rough sketch.

27. A projectile launched horizontally hits the ground in 0.5 seconds. If it had been launched
with a much higher speed in the same direction, it would have hit
the ground (neglecting the earth's curvature and air resistance) in __________.
28. In Chapter 2 we learned about "hang time," the time a jumper's feet are off the ground in a
vertical jump. If the jumper runs horizontally and has the same vertical component of takeoff
velocity, hang time will be __________. A) decreased. B) increased. C) no different.
29. A cannonball is launched horizontally from a tower. If the cannon has a barrel velocity of 100
m/s, where will the cannonball be 1 second later? _______ m horz, and ______ m vert. Now find
its displacement vector (distance and angle)
Mr. C’s Physics: Vectors and Projectiles Review & Study Guide                                                  Page 3 of 3
30. What is the resultant of a 4-unit vector and 3-unit vector at right angles to each other?

31. Which of the following would NOT be considered a projectile? A) A cannonball thrown straight
up B) A cannonball thrown through the air C) A cannonball rolling down a slope
D) A cannonball rolling off the edge of a table E) All of the above are projectiles.
32. A ball is hurled into the air at an angle of 30 degrees above the horizontal and lands on a target
that is at the same level as that where the ball started. The ball will also land on the target if it is
thrown at an angle of __________. A) 45° B) 55° C) 40° D) 60° E) none of the above
33. A ball is thrown straight upward at 20 m/s. Ideally (no air resistance), the ball will return to the
thrower's hand with a speed of __________.
34. In the absence of air friction, the horizontal component of a projectile's velocity doesn't change as
the projectile moves. A) Always true B) Always false C) Sometimes true
35. A ball thrown in the air will never go as far as physics ideally would predict because __________________
36. An object is dropped and falls freely to the ground with an acceleration
of 1 g. If it is thrown upward at an angle instead, its acceleration would be __________.
37. At what part of a path does a projectile have minimum speed?_____________________.

38. A ball falls off of a 78.4m cliff. How long does it take to hit the ground? ______________ How fast was it
going when it hit? __________________
39. A ball rolls horizontally off of a 78.4m cliff going 10m/s. How long does it take to hit the
ground? ____________How fast was it going when it hit? _________ m/s horz, and _________
m/s vert, so its actual speed was ____________________________________________________________
40. A rock is thrown straight up at 39.2m/s. What is its velocity at the peak? ____________How
long does it take to reach

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 views: 39 posted: 4/18/2010 language: English pages: 3