Unit 2 Physics

Define Kinematics

The study of motion without regards to what causes the motion

Define Scalar Quantity

A magnitude quantity not involving direction

Define Vector Quantity

A magnitude quantity involving direction

Define Distance

A scalar quantity depicting the magnitude of change

Define Displacement

A vector quantity depicting the magnitude of change in a certain direction

Define Speed

The rate of distance traveled with no regards to direction

Define Velocity

The rate of displacement

What is the formula for velocity?

displacement (delta x)/delta t

Define Average Velocity

The velocity over a period of time

Define Instantaneous Velocity

The velocity at a single moment

What two variables does Instantaneous Velocity involve?

Initial and Final Velocity

Define Initial Velocity

The beginning of a time period

Define Final Velocity

The end of a time period

Define Acceleration

The rate of change of velocity (slope)

Define Free Fall

• An object moving vertically under the influence of gravity

• NO air resistence or affects made by horizontal movement

• the acceleration is local; depends on spot in the universe

For an object in free fall, what forces act on the object besides gravity?

None, by definition, free fall means accelerating due to gravity only.

What can be concluded from Lab 4?

That acceleration is the ROC of velocity

What can be concluded from Lab 5?

• The d vs. t graph was quadratic, with values of (a=1/2g, b=Iv, and c=Iy)

• The V vs. t graph was linear with values of (m=g, b=Iv) (slope=a, which=g)

What is the slope of a Distance vs Time graph?

Velocity

What is the slope of a Velocity vs Time graph?

Acceleration

What are examples of scalar quantities?

time, temp, speed, mass

What are examples of vector quantities?

displacement, velocity, acceleration, force

What does “motion is relative” mean?

The motion of an object must be measured against (relative to) a different object. You cannot put the ruler on the object you are measuring.

What’s the difference between velocity and acceleration?

Velocity is how fast you are moving in a certain direction, acceleration is the rate at which the velocity is changing.

If a car is moving down the highway in a straight line at a constant 70 miles per hour, what is the car’s acceleration?

Zero

Of the quantities displacement, velocity, and acceleration, which one (s) can be negative?

All of them can be negative

Of the quantities displacement, velocity, and acceleration, which one(s) are vector quantities?

All of them are vector quantities

What is the rule for whether an object is speeding up or slowing down during acceleration based on the signs of initial velocity and acceleration?

• If initial velocity and acceleration have the same sign, the object will speed up.

• If initial velocity and acceleration have different signs, the object will slow down.

Can an object have a negative acceleration and still be speeding up? If yes, give an example.

If an object is initially heading in the negative direction, a negative acceleration is needed to make it go faster.

What device on cars is intended to produce zero acceleration?

Cruise Control

The terms linear regression, best fit line, trend line and regression line (curve) basically mean the same thing. What is the purpose of doing a regression on a set of data?

The purpose is to produce an equation of a line (or other shape curve) that actual data is most likely to be representing.

When producing a graph in Excel, you have been asked to display the equation of the line and the “r^2” value. What is the meaning of r^2?

It is the regression coefficient (squared.) It is an indication of how well the data fits on the regression (trend) line.

What is the range of r^2 and what is good value for r^2?

The range of r^2 is from 0 – 1. 0 is bad and represents no correspondence of the data to a line. 1 is the theoretical best and a value of 1 would indicate all the data points sit exactly on the regression line.

Using the convention that down is the negative direction and up is the positive direction, for an object in free fall that is moving down, what is the acceleration of gravity?

-9.81

Using the convention that down is the negative direction and up is the positive direction, for an object in free fall that is moving up, what is the acceleration of gravity?

-9.81

If you throw a ball up in the air at +15 m/s and it goes up, peaks out and falls back to the same spot you threw it from, what will its velocity be when it returns to your hand?

-15 m/s

If you throw a ball up in the air and 4.5 seconds to return to the same spot you threw it from, how long will it be in the air total?

9 s