Units
Measurement & Precision
Motion Basics
Definitions
Graphing Motion
100
What is the SI unit of mass?
kilogram, kg
100
How many significant figures are in 0.0450?
3
100
What is the formula for average speed?
s = d/t
100
A quantity with direction and magnitude
What is a vector quantity?
100
What does the slope of a distance-time graph represent?
Velocity
200
What is the SI unit of time?
seconds, s
200
How many significant figures are in the number 150?
2
200
What is the formula for average velocity?
200
A quantity with magnitude only and no direction.
What is a scalar quantity?
200
What does a horizontal line on a position vs. time graph indicate?
Constant position and zero velocity.
300
Which prefix means one-millionth and what is its symbol?
micro, mu
300
Describe the difference between accuracy and precision.
Accuracy is how close a measurement is to the correct value for that measurement.
The precision of a measurement system refers to how close the agreement is between repeated measurements (which are repeated under the same conditions).
300
A man is riding a horse with a constant velocity, when suddenly, the horse plants its feet and stops. When that happens, how will the man move relative to the horse?
The man will move forward relative to the horse.
300
The velocity at a given instant in time.
What is instantaneous velocity?
300
Describe what an accelerating object's graph looks like on a position vs. time graph.
changing slope
400
Convert 5 kilometers to meters
5000 meters
400
An experiment has only random errors in it. One student performs it ten times and averages her results. The other does it just one time and reports the result as his final answer. Most likely, which student will be more accurate?
The first.
400
You are told that object A has much more inertia than object B. If there are both traveling with the same velocity, which will be harder to stop?
Object A -- it has more mass and thus more inertia.
400
Explain the difference between velocity and acceleration.
Velocity is how fast an object changes position.
Acceleration is how fast an object changes velocity.
400
How can you find displacement from a position vs. time graph?
Change in position.
500
You see the following value in a lab notebook. What physical quantity was measured?
25 mph
Speed
Distance per time without direction
500
An experiment has systematic errors in it. One student performs it ten times and averages her results. The other does it just one time and reports the result as his final answer. Most likely, which student will be more accurate?
It won't really matter, since averaging doesn't help with systematic errors.
500
A moving object is experiencing a net force. Is it accelerating or not?
Yes -- there must be a change in velocity which is acceleration.
500
A force that resists motion when two bodies are in contact.
What is friction?
500
A graph shows a line curving upward on a position vs. time graph. What type of motion does this represent?
increasing speed, acceleration
600
A car travels 60 km in 1.5 hours. What is its average speed?
40km/hr
600
You ride your bicycle for 5.21 km west and then turn around and ride it 4.3 km east.
What is the total distance you traveled?
What is the total displacement?
distance, d = 5.21km + 4.3km = 9.5 km
displacement, Deltax=4.3km -5.21km=-0.9km
sigfigs to tenths place
600
You ride your bicycle with a velocity of 11 m/s west. If you do that until your displacement is 7.8 km west, how long will it take you?
710s
v=11 m/s west
Deltax=7.8km west
600
The tendency of a body to resist changes in its velocity.
What is inertia?
600
Refer to the graph below, for which the positive direction is north.
At what interval is the object south of the reference point?
9-14 seconds
700
You are walking with a constant velocity of 1.5 m/s north. If you walk for 15 minutes, what will be your displacement?
1,400 m north
v=(Deltax)/(Deltat) -> Deltax=v*Deltat
(15 min)/1*(60s)/(1min)=9.0*10^2 s
1.5 m/s*9.0*10^2 s=1400 m
700
What was the purpose of lab 1?
•Measure with different tools in the lab
•Observe source of Significant Figures
•Observing Math in the Real World (Relationship between area and dimensions)
•Observe relationships in data with graphing
700
Two bicycles are on the same road. One travels south at 23 km/hr, while the other travels south at 14 km/hr. What is the relative velocity, using the faster bicycle as the reference? If they never meet, which one is in front?
The relative velocity is 9 km/hr north, and the faster one would have to be in front.
700
What is Newton's 1st Law of Motion?
An object will remain at rest or will continue moving at a constant speed in a straight line unless acted upon by an external and unbalanced force.
700
refer to the graph below, for which the positive direction is north
At what time or times is there acceleration?
t = 4s, 6s, 10s, 12s, 16s