Physics 011
Chapter 2
Answers of MC#2A



1. 

A bird
flies 4.0 meters due north in 2.0 seconds and then flies 2.0 meters due west
in 1.0 seconds. What is the bird's average speed? 




2. 

If a car
is travelling due south with a decreasing speed, then the direction of the
car's acceleration is 




3. 

A hiker travels
60 meters north and then 120 meters south. What is her resultant
displacement? See Section 21 




4. 

If the
average speed of a plane is 500 km per hour, how long will it take to fly 125
km? See Section 22 




5. 

Applying
the brakes to a car traveling at 45 km/h provides an acceleration of 5.0 m/s^{2}
in the opposite direction. How long will it take the car to stop? See Section 25 




6. 

A ball
rolls down a frictionless inclined plane with a uniform acceleration of 1.0
m/s^{2}. If its velocity at some instant of time is 10 m/s, what will
be its velocity 5.0 seconds later? See Section 25 




7. 

A ball
rolls down a frictionless inclined plane with a uniform acceleration of 1.0
m/s^{2}. If its initial velocity is 1.00 m/s, how far will it travel
in 10 s? See Section 25 




8. 

A body
with an initial speed of 25 m/s accelerates uniformly for 10 seconds to a
final speed of 75 m/s. What is the acceleration? 




9. 

A body
initially at rest is accelerated at 5 m/s^{2} for 10 seconds. What is
its final velocity? See Section 25 




10. 

Which
graph represents the motion of a body starting from rest and moving with a
constant nonzero acceleration? 




11. 

The speeds
of a body at the ends of five successive seconds are: 180, 360, 540, 720, 900
m/h. What is the acceleration of the body? See Section 24 




12. 

"An object is initially at rest then moves in a straight line and accelerates uniformly at a rate of 2.00 m/s^{2}." After the
object has been in motion for four seconds, its speed would be ___ m/s. 




13. 

"An object is initially at rest then moves in a straight line and accelerates uniformly at a rate of 2.00 m/s^{2}." The
distance traveled by the object during the first five seconds of its travel
was ___ m. See Section 25 




14. 

"An object is initially at rest then moves in a straight line and accelerates uniformly at a rate of 2.00 m/s^{2}." The
average speed of the object during the first six seconds of its travel was
___ m/s. See Section 25 




15. 

"An object is initially at rest then moves in a straight line and accelerates uniformly at a rate of 2.00 m/s^{2}." The
average speed of the object during the third second of its motion was ___
m/s. 




16. 

"An object is initially at rest then moves in a straight line and accelerates uniformly at a rate of 2.00 m/s^{2}." The
distance traveled by the object during the fourth second of its travel was
___ m. See Section 25 




17. 

"An object of mass m initially at rest experiences a constant acceleration of magnitude a_{o}. After a time interval t_{o} has elapsed, the speed of the car is v_{o} and it has traveled a distance d_{o}." After a
total time 3 t_{o} has elapsed, the speed of the object will be v_{o}x
___. See Section 25 




18. 

"An object of mass m initially at rest experiences a constant acceleration of magnitude a_{o}. After a time interval t_{o} has elapsed, the speed of the car is v_{o} and it has traveled a distance d_{o}." After a
total time 2 t_{o} has elapsed, the distance traveled by the object
will be d_{o}x ___. See Section 25 




19. 

"Six different objects are observed to move in a straight line. Some aspect of the motion of each of the six objects is plotted as a function of time in the following graphs." Which
graph(s) represent(s) a situation in which the object moved with a constant
nonzero acceleration? See Section 28 




20. 

"Six different objects are observed to move in a straight line. Some aspect of the motion of each of the six objects is plotted as a function of time in the following graphs." Which
graph represents a situation in which the object moved with a constant zero
acceleration? See Section 28 




21. 

"An object is observed to move in a straight line. Some aspect of the motion of this object is plotted as a function of time in the following graph." The slope of the dashed line in the graph above represents ___. 




22. 

"An object is observed to move in a straight line. Some aspect of the motion of this object is plotted as a function of time in the following graph." The slope of the dashed line in the graph above represents ____. See Section 28 




23. 

"An object is observed to move in a straight line. Some aspect of the motion of this object is plotted as a function of time in the following graph." The shaded area in the graph above represents ___. See Section 28 




24. 

"An object is observed to move in a straight line. Some aspect of the motion of this object is plotted as a function of time in the following graph." The shaded area in the graph above represents ___. See Section 28 




25. 

"The speed of an object moving in a straight line changes with time as in the figure below." For which of the time intervals was the average speed of the object
greatest? See Section 28 




26. 

"The speed of an object moving in a straight line changes with time as in the figure below." During which time interval did the object travel with a constant nonzero
acceleration? See Section 28 




27. 

"The speed of an object moving in a straight line changes with time as in the figure below." During which time interval was the average speed least? See Section 28 




28. 

"The speed of an object moving in a straight line changes with time as in the figure below." During which time interval did the maximum value of the magnitude of the
instantaneous acceleration occur? See Section 28 




29. 

"The speed of an object moving in a straight line changes with time as in the figure below." During which time interval was the speed of the object constant? 




30. 

"The speed of an object moving in a straight line changes with time as in the figure below." During which time interval did the minimum value of the instantaneous
speed occur? 




31. 

"The speed of an object moving in a straight line changes with time as in the figure below." During which time interval was the magnitude of the average acceleration
greatest? 




32. 

"The speed of an object moving in a straight line changes with time as in the figure below." During which time interval was the magnitude of the average acceleration
least? See Section 28 




33. 

"For this question, assume that g = 10.00 m/s^{2}. A small stone originally at rest is dropped over the edge of a very tall building." During the fourth second of the fall, the speed of the stone changes ___ m/s.





34. 

"For this question, assume that g = 10.00 m/s^{2}. A small stone originally at rest is dropped over the edge of a very tall building." During the
second second of fall, the average speed of the stone is ___ m/s. See Section 27 and/or 25 




35. 

"For this question, assume that g = 10.00 m/s^{2}. A small stone originally at rest is dropped over the edge of a very tall building." During the
first second of fall, the stone falls a distance of ___ m. 




36. 

"For this question, assume that g = 10.00 m/s^{2}. One reaches out over the edge of a tall building and throws a stone straight up with an initial speed of 20.00 m/s." The change in speed of the stone during the first second of its motion is
___ the change in its speed during the third second of its motion. See Section 27 and/or 25 




37. 

"For this question, assume that g = 10.00 m/s^{2}. One reaches out over the edge of a tall building and throws a stone straight up with an initial speed of 20.00 m/s." The
distance traveled by the stone during the 1st second is ___ the distance
traveled by the stone during the 2nd second. See Section 27 and/or 25 




38. 

"For this question, assume that g = 10.00 m/s^{2}. One reaches out over the edge of a tall building and throws a stone straight up with an initial speed of 20.00 m/s." At the
instant the stone is at its maximum altitude, the acceleration of the stone
is ___. See Section 27 and/or 25 




39. 

"For this question, assume that g = 10.00 m/s^{2}. One reaches out over the edge of a tall building and throws a stone straight up with an initial speed of 20.00 m/s." The time
required for the stone to reach its maximum altitude is ___ sec. See Section 27 and/or 25 
