Vocabulary
Define motion.
Change in an object's position relative to a reference point.
Define hypothesis.
It is a prediction or a possible solution that can be tested in an experiment.
Define speed.
Speed is the distance an object travels per unit of time.
What is the equation for acceleration?
a = change in velocity ÷ change in time
Velocity can be calculated by which equation?
V = speed ÷ time
What is a vector?
What is a scalar?
Vector - quantity that has both magnitude and direction.
Scalar - quantity specified completely by a number and units. It has no direction.
What is a factor that does not change in an experiment?
Constant
During a given time interval the average velocity of an object is zero. What can you conclude about its displacement over the time interval?
The displacement is zero.
When velocity is positive and acceleration is negative, what happens to the object's motion?
The object slows down.
What is constant velocity?
No change in direction.
No change in speed.
The distance between an object and a reference point is the object's __________.
position
A quantity in an experiment that can have more than one value is a(n) __________.
variable
What does the slope of a distance vs time graph represent? What does a steeper line mean?
The slope of a distance vs time graph is the object's speed. The steeper the graph, the greater the speed of the object.
What is the slope of a line on a velocity vs time graph?
An object's acceleration.
If a baseball has a negative velocity and a negative acceleration, the velocity _____________.
decreases.
What is an object's displacement?
It is the distance and direction between the final position and starting position of the object.
What is the control group in an experiment?
It is the standard by which test results can be compared.
A car is moving in a constant direction on a horizontal road. The velocity vs time graph of the car's motion shows a straight line with a negative slope. What does the line tell you about the car's speed?
The car's speed is decreasing.
Calculate how long it takes for a stone falling from a bridge with an average acceleration downward of 9.8 m/s2 to hit the water. The stone starts from rest and hits the water with a velocity of 12.3 m/s.
1.26 seconds
Define centripetal acceleration.
It is the acceleration toward the center of a curved or circular path.
Explain the difference between instantaneous speed and average speed.
Instantaneous speed - is the speed of an object at a specific moment in time during the motion of an object.
Average speed - is the speed of an object throughout the complete motion of the object. The total distance traveled divided by the total time of travel.
Explain the difference between the independent variable and the dependent variable.
Independent variable - is the variable that is changed to test the effect on the dependent variable.
Dependent variable - this variable changes according to the changes of the independent variable.
A missile is launched with a speed of 350 m/s and flies for 250 km. Then it changes speed to 200 m/s and travels a distance of 175 km until reaching its target. What is the total flight time for the missile in hours?
Answer = 0.44 hours
If a subway train is moving to the left (has a negative velocity) and then comes to a stop, what is the direction of its acceleration? Is the acceleration positive or negative?
The acceleration is to the right. The acceleration is positive or less negative.
Kristie walks once around a large circle at a constant speed. What is her average velocity for the whole walk? Explain using equations. Is Kristie’s instantaneous velocity constant? Explain this second part in words.
Her average velocity is zero, because displacement is zero.
Kristie's instantaneous velocity is not constant. It is changing every change in direction.