Physics 011
Chapter 3: Kinematics in Two Dimensions; Vectors
Practice Questions
A of PQ#3


1. 

If you
drive west at 20 km/h for one hour, then drive east at 15 km/h for one hour,
your net displacement will be See Section 32 in Giancoli. The west velocity is greater than the East velocity. 


2. 

A 200lb force is pulling on an object, as shown. The sign of the x and y
components of the force are Left is negative. See Section 34 in Giancoli. 


3. 

Three boys each pull with a 20N force on the same object. The resultant
force will be See Section 32 in Giancoli. 


4. 

Consider a
plane flying with groundspeed Vg and airspeed Va in a wind with speed V.
Which of the following relationships is true? See Example 312 in Giancoli. 


5. 

Two
vectors, R and S, are known: If vector S is subtracted from vector R, the vector T = R  S is Review Section 33 in Giancoli. 


6. 

Two
vectors, R and S, are known: If vector R is subtracted from vector S, the vector T = S  R is Review Section 33 in Giancoli. 


7. 

Two
vectors, R and S, are known: If vector S is added to the vector R, then the vector T = R + S is 


8. 

If the
acceleration vector of a body is perpendicular to the velocity vector, which
of the following must be true? This will never be true if the acceleration is perpendicular to the velocity. See Section 35 in Giancoli. 


9. 

A vector
of magnitude 10 has an angle with the positive xaxis (East) of 120 degrees.
What are its components? This would be true if the vector was in the first quadrant. Review Section 34 in Giancoli. 


10. 

A vector
of magnitude 10 has an angle with the positive xaxis (East) of 60 degrees.
What are its components? This would be true if the vector was in the first quadrant. Review Section 34 in Giancoli. 


11. 

A vector
has components x=6 m and y=8 m. What is its magnitude and direction? Your magnitude is correct. Review Section 34 in Giancoli. 


12. 

A vector
has components x= 2 m and y=2 m. What is its direction (angle with respect
to East)? This answer is in the first quadrant. Review Section 34 in Giancoli. 


13. 

Three
vectors have components (x,y):A=(2,3),B=(4,7) and C=(6,3).
What is the magnitude of the resultant vector (D=A+B+C)? The magnitude is always positive. Review Section 34 in Giancoli. 


14. 

Three
vectors have components (x,y):A=(2,3),B=(4,7) and C=(6,3).
What is the magnitude of the resultant vector (D=ABC)? 


15. 

Suppose
that several projectiles are fired on level ground. Which one will be in the
air longest? Review example 34 in Giancoli. 


16. 

Which of
the following does not affect the range of a projectile? Review Example 38 in Giancoli. 


17. 

Which of
the following must be zero for a projectile to achieve its maximum range? If this were true the projectile would not have moved at all. See Example 37 in Giancoli. 


18. 

Which of
the following must be zero for a projectile to be at its maximum height? Its elevation is independent of its horizontal motion. See Example 34 in Giancoli. 


19. 

You hit a
handball too hard and it lands, moving horizontally, on top of a roof. If its
original velocity was v_{o} at an angle q above the horizontal, then
the velocity it lands on the roof with is Good try, but still wrong. Projectile motion ends just before the projectile hits the ground. See Example 34 in Giancoli. 


20. 

You
throw a pebble upward as shown, with a velocity v_{o} at an angle
theta, from a roof (at point J) h ft above the ground. If the pebble rises
upward to h ft above the roof (to point K), then falls to the ground below
(to point L), its speed when it hits the ground is This is the maximum speed it would have upon passing the roof on the way down. Review Section 36 in Giancoli. 


21. 

Taking
"up" as positive at the highest point, the acceleration of a
projectile is 


22. 

If the sum
of two vectors equals zero, the magnitude of their difference is 


23. 

A sailboat
travelling with a speed of 4 knots heads directly up river against a 3 knot
current. Its speed over ground is The boat speed is measured with respect to the water and the water is moving over the ground. Review Section 38 in Giancoli. 


24. 

A sailboat
travelling with a speed of 4 knots heads directly down river with a 3 knot
current. Its speed over ground is Remember that they are in the same direction. Review Section 38 in Giancoli. 


25. 

A sailboat
travelling with a speed of 4 knots heads directly across a river which has a
3 knot current. Its speed over ground is 