Scalars and Vectors
What is a Scalar?
A quantity which is fully described by magnitude alone
Calculate the average speed of a teacher that does the following motion in 10 seconds:
i. walks 2m, south
ii. walks 4m, east
iii. walks 2m, north
iv. walks 4m, west
1.2 m/s
A motorcycle decreases in speed from 25 m/s to 5 m/s, is the motorcycle accelerating?
Yes
What is a Vector?
A quantity which is fully described my magnitude and direction
An object that is NOT accelerating MUST _______. Choose all that apply
a) be at rest
b) be moving and moving with a constant speed
c) be changing its direction
d) be maintaining a constant velocity
D
Identify the following quantity as being a scalar or a vector:
30km/hr
Scalar
Grandma H challenges Michael Johnson in the 400 meter dash. Grandma H spins her wheelchair wheels five times and gives up 15 meters from the starting line. MJ makes a complete circle around the track and stops at the starting line. What is the displacement of MJ and what is the displacement of Grandma H?
MJ displacement = 0 m
Grandma H displacement = 15 m
Calculate the average velocity of a teacher that does the following motion in 10 seconds:
i. walks 2m, south
ii. walks 4m, east
iii. walks 2m, north
iv. walks 4m, west
0 m/s
Which 3 controls on an automobile cause an acceleration?
gas pedal, brake pedal, steering wheel
There is no time interval with negative velocity
Which of the following measurements are Vectors?
Distance
Displacement
Speed
Velocity
Acceleration
Displacement, Velocity and Acceleration
A football coach walks 12 meters westward, then 16 meters eastward, then 22 meters westward, and finally 6 meters eastward.
What is the distance moved?
What is the magnitude and direction of the displacement?
Distance: 56 m
Displacement: 12 m West
A car with a rightward velocity and a leftward acceleration is _______.
a) moving to the left and speeding up
b) moving to the left and slowing down
c) moving to the right and speeding up
d) moving to the right and slowing down
e) Two or more of the above are possible
D
What is the difference between speed and velocity?
(Speed is a scalar, velocity is a vector)
Velocity is speed with a direction
A tennis ball moves 16 meters northward, then 22 meters southward, then 12 meters northward and finally 32 meters southward.
What is the distance moved?
What is the magnitude and direction of the displacement?
Distance: 82 m
Displacement: 26 m south
Which of the following statements are true?
a) Speed is a vector
b) When calculating speed, direction is not important
c) Velocity is a vector
d) Velocity is speed with a direction
e) When calculating Speed, you need to find the displacement of an object over time
f) When calculating Velocity, you need to find the distance travelled over time
B, C, D
A baseball is falling downwards from the peak of its trajectory and speeding up at a constant rate. The direction of the baseball's acceleration _________.
a) upward
b) downward
c) neither; there is no acceleration
d) .... nonsense! Acceleration does not have a direction associated with it
B