Calculating Speed
What is the average speed of a train that covers a distance of 180 kilometers in 90 minutes?
A) 2.0 km/min B) 1.5 km/min C) 120 km/h D) 180 km/h
A) 2.0 km/min
3. Look at the distance-time graph.
What is the average speed of the object between the 5-second mark and the 10-second mark, assuming the motion is uniform? (The graph shows the object travels 50 meters in 10 seconds.)
A) 50 m/s B) 10 m/s C) 5 m/s D) 2.5 m/s
C) 5 m/s
Speed is a scalar quantity, defined as the rate of change of distance. Velocity is a vector quantity, defined as the rate of change of {______} and includes the {______} of motion. Which terms best complete the sentence?
A) displacement, time
B) distance, magnitude
C) displacement, direction
D) distance, direction
C) displacement, direction
A distance-time graph shows the motion of two objects, Object A and Object B. The line for Object A is steeper than the line for Object B. According to the graph, what can you conclude about the motion of the two objects?
A) Object B is moving faster than Object A.
B) Object A traveled for a longer time than Object B.
C) Object A has a greater average speed than Object B.
D) Both objects are moving at the same constant speed.
C) Object A has a greater average speed than Object B.
What is the term for the unseen push or pull that can cause an object to change its motion or shape?
Force
A remote-controlled airplane flies an average of 450 meters in 30 seconds during a test flight. What is the airplane’s average speed in meters per second?
A) 15 m/s B) 150 m/s C) 0.067 m/s D) 45 m/s
A) 15 m/s
A distance-time graph shows a straight line sloping upward from
(0 s,0 m). What type of motion does this represent?
Constant speed (or constant velocity or uniform motion)
What is the difference between speed and velocity?
Speed: The rate at which an object covers distance.
Velocity: The rate at which an object changes its displacement. (Includes Direction)
A distance-time graph shows a horizontal line segment between the time marks of 10 seconds and 20 seconds. Which event would best explain the object's motion during this 10-second interval?
A) The object is accelerating rapidly.
B) The object is moving at a constant, high speed.
C) The object is remaining stationary (not moving).
D) The object is slowing down to a stop.
C) The object is remaining stationary (not moving).
A book is resting motionless on a table. According to Newton’s First Law of Motion, what is true about the forces acting on the book?
A) The net force acting on the book is zero.
B) There are no forces acting on the book.
C) The only force acting on the book is gravity.
D) The force of the table pushing up is greater than the force of gravity.
A) The net force acting on the book is zero.
A swimmer crosses a pool that is 50 meters long in 40 seconds. What is the swimmer's average speed in meters per second (m/s)?
1.25 m/s (Calculated as 50 m/40 s)
A graph shows an object traveled 20 meters in the first 4 seconds. What was the object's average speed during this interval?
5 m/s (Calculated as 20m/4s)
To convert an object's speed into its velocity, you must specify this additional piece of information.
direction
A distance-time graph shows a horizontal line at 75 meters. What must the object's speed be during the time represented by this line segment?
Zero or 0 m/s.
According to Newton's First Law of Motion, an object at rest will remain at rest unless acted upon by this type of force.
An unbalanced force (or A net force)
A jet flies 2,500 kilometers in 3.5 hours. Calculate the jet's average speed, rounded to the nearest whole number, in kilometers per hour (km/h).
714 km/h
2500 km / 3.5 h
On a distance-time graph, the line changes from being steep to being less steep. What physical change in the object's motion does this indicate?
The object is slowing down or decreasing its speed.
A weather report states that a storm is moving at 25 km/h. A separate report mentions a hurricane is tracking northeast at 180 km/h. Given this information above, which weather phenomenon has a known velocity? Can you determine the velocity of the other phenomenon?
A) Only the storm has a known velocity; the hurricane's velocity is unknown.
B) Only the hurricane has a known velocity; the storm’s velocity is unknown.
C) Both have a known velocity.
D) Neither has a known velocity.
B) Only the hurricane has a known velocity; the storm’s velocity is unknown.
A distance-time graph shows an object is stationary at 20 meters for the first 10 seconds. It then moves 30 meters in the next 5 seconds. What is its average speed during the entire 15-second trip?
2 m/s (Calculated as Total Distance / Total Time: 30m/15s)
A student pushes a box with a force of 15 N to the right, while friction exerts a 5 N force to the left. What is the net force on the box?
10 N to the right (Calculated as 15 N−5 N)
A boat travels at a constant speed of 20 km/h. How many hours will it take the boat to travel a distance of 5 kilometers?
.25 hours
A graph shows an object moved 30 m from t=0 s to t=5 s, and then moved an additional 10 m from t=5 s to t=10 s. What was the average speed of the object during the entire 10-second trip?
4 m/s (Calculated as Total Distance / Total Time:
30m+10m =40m
10s 10s
A runner completes a 400-meter lap on a circular track and finishes exactly where they started. Which of the following statements best describes the difference between the runner's average speed and average velocity?
A) Both average speed and average velocity are zero.
B) The average speed is zero, but the average velocity is non-zero.
C) The average speed is non-zero, and the average velocity is zero.
D) Both average speed and average velocity are non-zero.
C) The average speed is non-zero, and the average velocity is zero.
An athlete runs 5 km in 30 minutes, then rests for 15 minutes, and finally sprints another 2 km in 5 minutes. A distance-time graph is created to show this motion. Four points representing the end of each stage are listed in no particular order:
7 km, 50 min
5 km, 30 min
5 km, 45 min
0 km, 0 min
Which is the correct order of the points from the start of the motion to the end of the motion?
A) 4, 1, 2, 3
B) 4, 3, 2, 1
C) 4, 2, 3, 1
D) 2, 4, 3, 1
C) 4, 2, 3, 1
Part A: A tugboat is pulling a barge toward the dock. The forward force from the tugboat's engine is 50,000 N, and the opposing drag/friction force from the water is 45,000 N. The net force on the barge is {______} N and acts {______}.
A) 95,000, backward
B) 5,000, backward
C) 5,000, forward
D) 50,000, forward
C) 5,000, forward