Curriculum
Course: American System Physics
time left:
:
:
Login

Curriculum

American System Physics

A Physics Toolkit

0/9

Representing Motion

0/9

Accelerated Motion

0/9

Forces in One Dimension

0/9

Displacement and Force in Two Dimensions

0/9

Motion in Two Dimensions

0/9

Gravitation

0/9

Rotational Motion

0/9

Momentum and Its Conservation

0/9

Energy and Its Conservation

0/9

Thermal Energy

0/9

States of Matter

0/9

Vibrations and Waves

0/9

Sound

0/9

Fundamentals of Light

0/9

Reflection and Refraction

0/9

Interference and Diffraction

0/9

Electrostatics

0/9

Electric Current and Circuits

0/9

Magnetic Fields

0/9

Electromagnetic Induction and Electromagnetism

0/9

Quantum Theory and the Atom

0/9

Solid-State Electronics

0/9

Nuclear and Particle Physics

0/9
Quiz

6.3 Relative Velocity – Quiz

Submit quiz
Once you submit, you will no longer be able to change your answers. Are you sure you want to submit the quiz?
Cancel Submit

Relative Velocity American Physics quiz: free practice for American System Physics. Work through this Relative Velocity American Physics quiz and get instant feedback on every answer. If you get stuck, review the 6.3 Relative Velocity — Notes lesson. More practice: American System Physics — all units. Syllabus: OpenStax free science textbooks.

  • Questions count: 50
  • Passing grade: A-
  • Time limit:
Start Quiz
1.
The table gives the speeds of a lorry and a car behind it in the same lane, both heading east. How fast does the car close in on the lorry?
7.00 m/s
55.0 m/s
27.5 m/s
24.0 m/s
2.
Two cyclists ride toward each other at 6.5 m/s and 5.5 m/s relative to the road. At what rate does the gap between them shrink?
1.00 m/s
12.0 m/s
6.00 m/s
8.50 m/s
3.
A passenger walks toward the front of a train at 1.2 m/s while the train moves at 28 m/s. What is the passenger's speed relative to the track?
26.8 m/s
1.20 m/s
29.2 m/s
28.0 m/s
4.
During cruise at 240 m/s, a steward strolls 1.5 m/s toward the tail of the aircraft. How fast is he moving over the land below?
242 m/s
1.50 m/s
240 m/s
238 m/s
5.
A kayak paddles straight across a 90 m wide river at 1.8 m/s relative to the water. The current flows at 1.2 m/s. How long does the crossing take?
50.0 s
41.6 s
150 s
75.0 s
6.
A kayak crosses a 90 m wide river pointing straight across at 1.8 m/s relative to the water in a 1.2 m/s current. How far downstream does it land?
90.0 m
60.0 m
135 m
49.9 m
7.
A rowing boat heads straight across at 3.0 m/s relative to water in a 4.0 m/s current. What is its speed relative to the bank?
7.00 m/s
1.00 m/s
5.00 m/s
3.00 m/s
8.
A ferry must dock directly opposite its start. Using the data in the table, how should it be pointed?
21.8° upstream from straight across
23.6° downstream from straight across
Straight across
23.6° upstream from straight across
9.
A ferry (5.0 m/s in water, 2.0 m/s current) crosses a 120 m river aiming to land directly opposite. How long does it take?
26.2 s
24.0 s
22.3 s
40.0 s
10.
The table gives flight data for a light aircraft. What is its ground speed?
225 km/h
186 km/h
135 km/h
180 km/h
11.
For that aircraft (180 km/h north through the air, wind 45 km/h toward the east), in which direction does it travel over the ground?
14.0° west of north
76.0° east of north
14.0° east of north
due north
12.
A pilot with airspeed 300 km/h wants to fly due north while the wind blows toward the west at 60 km/h. What heading should she choose?
11.5° west of north
due north
14.0° east of north
11.5° east of north
13.
If a bus moves at +15 m/s relative to a cyclist, what is the cyclist's velocity relative to the bus?
−15 m/s
+15 m/s
0 m/s
+30 m/s
14.
Which equation correctly chains relative velocities for a swimmer (s), river water (w) and ground (g)?
v(s/g) = v(s/w) − v(g/w) + v(w/s)
v(s/g) = v(s/w) + v(w/g)
v(s/g) = v(w/s) + v(g/w)
v(s/g) = v(s/w) × v(w/g)
15.
What is meant by a plane's airspeed?
Its velocity relative to the ground
The speed of the wind
Its velocity relative to the surrounding air
Its vertical speed
16.
Why can a boat never land directly opposite its start if the current is faster than the boat's speed through the water?
The river is too wide
The boat's speed increases in a fast current
Relative velocities only add in one dimension
No heading gives an upstream component large enough to cancel the current
17.
Using the values on the river diagram, how far downstream from its starting point does the boat reach the north bank?
Dr Dabour Hub Academy - figure 1
32.0 m
80.0 m
200 m
29.7 m
18.
A rowing boat crosses as drawn. How fast does it move over the riverbed, as judged by someone standing on the bank?
Dr Dabour Hub Academy - figure 2
4.20 m/s
3.23 m/s
1.80 m/s
3.00 m/s
19.
An observer on the ground tracks the plane whose vectors are drawn. What speed does she measure?
Dr Dabour Hub Academy - figure 3
310 km/h
190 km/h
257 km/h
250 km/h
20.
For the plane in this diagram, which describes its track over the ground?
Dr Dabour Hub Academy - figure 4
17.4° east of north
due north
72.6° west of north
17.4° west of north
21.
Using the diagram, what is the velocity of car A relative to car B?
Dr Dabour Hub Academy - figure 5
7 m/s to the right
45 m/s to the right
7 m/s to the left
26 m/s to the right
22.
How fast, and in which direction, does car B move as seen by the driver of car A in this head-on diagram?
Dr Dabour Hub Academy - figure 6
4 m/s to the left
40 m/s to the left
40 m/s to the right
18 m/s to the left
23.
The vector triangle shows a boat pointed upstream so that its resultant R is straight across. What is the magnitude of R?
Dr Dabour Hub Academy - figure 7
5.5 m/s
4.3 m/s
3.71 m/s
2.5 m/s
24.
In a flume experiment, the drift of a toy boat was measured for several current speeds (graph). The gradient equals the crossing time. What is the boat's speed relative to the water?
Dr Dabour Hub Academy - figure 8
6.00 m/s
2.00 m/s
18.0 m/s
0.500 m/s
25.
Using the rules in the table, what is the relative speed of two trains passing on parallel tracks in opposite directions at 33 m/s and 27 m/s?
60.0 m/s
6.00 m/s
30.0 m/s
33.0 m/s
26.
Rank the flights in the table from greatest to least ground speed.
Flight 3, Flight 1, Flight 2
Flight 1, Flight 3, Flight 2
Flight 2, Flight 3, Flight 1
All the same
27.
Which trial in the flume results table is anomalous?
Trial 1
Trial 2
Trial 4
Trial 3
28.
Excluding the anomaly, use the mean time and mean drift in the table to find the speed of the water.
0.399 m/s
3.34 m/s
0.335 m/s
0.299 m/s
29.
Using the same table (excluding the anomaly), what is the boat's speed relative to the water?
0.399 m/s
0.299 m/s
2.51 m/s
0.500 m/s
30.
How should a student measure a toy boat's speed relative to the water before testing it in a current?
Time it across the flowing flume once
Time it over a measured distance in still water several times and average
Measure only its drift
Estimate it from the motor's size
31.
A coordinate system with an observer, used to measure positions and velocities, is a frame of _____.
motion
velocity
equilibrium
reference
32.
The direction in which a boat or plane is pointed is called its _____.
heading
track
drift
airspeed
33.
The velocity of an aircraft relative to the ground is its _____.
airspeed
ground speed
heading
crosswind
34.
The velocity of B relative to A is exactly the same as the velocity of A relative to B. True or false?
True
True only when both move the same way
False, because v(B/A) = −v(A/B): equal size, opposite direction
False, because relative velocities are always zero
35.
Pointing a boat straight across a river gives the shortest possible crossing time. True or false?
False, because pointing upstream is always quicker
False, because the current always lengthens the crossing
True only when the current is slow
True
36.
A swimmer slower than the current can still reach the point directly opposite by aiming upstream. True or false?
False, because this needs v_swimmer > v_water so the upstream component can cancel the current
True
True only when she aims at 45°
False, because swimmers can never cross rivers
37.
A plane's ground velocity is the vector sum of its air velocity and the wind velocity. True or false?
False, because ground speed equals airspeed
True
False, because the wind is subtracted as a scalar
True only when the wind is a tailwind
38.
Cars travelling in the same direction at 30 m/s and 25 m/s have a relative speed of 55 m/s. True or false?
True
True only when they are on a curve
False, because in the same direction the relative speed is the difference, 5 m/s
False, because relative speed is always zero
39.
A river current changes where a boat lands but not how long it takes when the boat points straight across. True or false?
False, because the current always increases the time
False, because the current reduces the time
True only when the current is weak
True
40.
An aircraft's heading is always the direction in which it travels over the ground. True or false?
False, because a crosswind adds a sideways component, so the track differs from the heading
True
True only when the wind is strong
False, because aircraft have no heading
41.
Velocities can only be added if they point along the same line. True or false?
True
False, because velocities add as vectors in any direction, using components or Pythagoras
True only when they are perpendicular
False, because velocities can never be added
42.
In v(a/c) = v(a/b) + v(b/c), the inner subscripts must match. True or false?
False, because the outer subscripts must match
False, because subscripts do not matter
True
True only when everything is one-dimensional
43.
A passenger walking backward at 1.5 m/s in a train moving at 20 m/s moves at 18.5 m/s relative to the ground. True or false?
False, because it is 21.5 m/s
False, because it is 1.5 m/s
True only when the train accelerates
True
44.
The ground frame is fixed to Earth's surface and is used for most everyday velocities. True or false?
True
False, because the ground frame moves with the wind
False, because no frame is used in everyday life
True only when the object is a car
45.
Aiming a boat upstream so it lands directly opposite makes the crossing slower than pointing straight across. True or false?
False, because aiming upstream makes it faster
True
False, because both take the same time
True only when the river is narrow
46.
A boat pointed straight across at 6 m/s in an 8 m/s current moves at 10 m/s relative to the bank. True or false?
False, because the speeds simply add to 14 m/s
False, because the answer is 2 m/s
True
True only when the river is wide
47.
Repeating drift measurements and averaging them reduces random error in a river-crossing experiment. True or false?
False, because averaging removes systematic error only
False, because repeats increase random error
True only when the current is steady
True
48.
If a toy boat is pointed slightly downstream instead of straight across, the measured drift will be systematically too large. True or false?
True
False, because heading has no effect on drift
False, because drift would be too small
True only when the flume is short
49.
In a flume investigation of drift against current speed, the boat's speed through the water is a control variable. True or false?
False, because it is the dependent variable
True
False, because it is the independent variable
True only when the flume is wide
50.
Timing a toy boat across a 4 m flume with a stopwatch has a larger percentage uncertainty than timing it across a 40 m pond. True or false?
False, because uncertainty is the same for any distance
False, because shorter times are more precise
True
True only when the boat is fast
  • 1
  • 2
  • 3
  • 4
  • 5
  • 6
  • 7
  • 8
  • 9
  • 10
  • 11
  • 12
  • 13
  • 14
  • 15
  • 16
  • 17
  • 18
  • 19
  • 20
  • 21
  • 22
  • 23
  • 24
  • 25
  • 26
  • 27
  • 28
  • 29
  • 30
  • 31
  • 32
  • 33
  • 34
  • 35
  • 36
  • 37
  • 38
  • 39
  • 40
  • 41
  • 42
  • 43
  • 44
  • 45
  • 46
  • 47
  • 48
  • 49
  • 50
Part of Motion in Two Dimensions — see every lesson and quiz in this unit.
Accepted payment methods