Physics Unit 2 Test

What is a frame of reference?

In physics, a frame of reference is the background against which the motion of an object is compared (e.g ground to an object)

What is the difference between distance and displacement?

Distance is the total length of the path taken by an object in motion, regardless of direction (only magnitude), whereas displacement is the change in position of an object (magnitude and direction).

What is the difference between speed and velocity?

Speed is the rate at which an object moves from one place to another, (magnitude only), while velocity is the rate at which an object changes its position, including both magnitude and direction.

Speed =

distance/time (actually gives average speed)

What is average velocity?

Average velocity is displacement/time. It includes both magnitude and direction, contrasting with average speed, which is only concerned with distance (magnitude).

What is instantaneous velocity?

Instantaneous velocity is the velocity of an object at a specific moment in time, representing the rate of change of position with respect to time, including both magnitude and direction. Requires calculus.

How is average speed different from average velocity?

Average speed measures distance traveled over time, while average velocity accounts for displacement over time and includes direction.

Does a car’s speedometer measure average or instantaneous speed?

A car's speedometer measures instantaneous speed, reflecting the exact speed of the vehicle at any given moment.

What is acceleration?

Acceleration is the rate at which a velocity changes, calculated using change in velocity over time. Any change in the velocity of an object is an acceleration (speeding up, slowing down, changing direction)

What does the greek letter Δ represent? What does Δy represent?

The Greek letter Δ represents a change in a quantity. Δy specifically represents the change in displacement of an object.

What are the units for displacement, velocity, and acceleration?

Displacement: measured in meters (m)

Velocity: measured in meters per second (m/s)

Acceleration: measured in meters per second squared (m/s²)

Is 55 mph a velocity, or a speed?

55 mph is a speed because it describes how fast an object is moving without specifying its direction.

How is an object at rest represented on a p/t graph?

An object at rest is represented on a position-time (p/t) graph as a horizontal line, indicating that its position remains constant over time.

How is an object at rest represented on a v/t graph?

An object at rest is represented on a velocity-time (v/t) graph as a horizontal line at the x-axis, indicating that it is not changing its speed over time.

What does a positively sloped line on a p/t graph represent? A negatively sloped line?

A positively sloped line represents a constant positive velocity on a p/t graph, while a negatively sloped line represents a constant negative velocity.

On a p/t graph, what does the slope give us?

The slope on a position-time (p/t) graph gives us the velocity of the object, indicating how quickly the object's position changes over time.

What does a curved line on a p/t graph represent and why?

A curved line on a position-time (p/t) graph represents a non-constant velocity, meaning the object is experiencing an acceleration.

On a V/T graph what does a horizontal line represent?

A horizontal line on a velocity-time (V/T) graph represents constant velocity, indicating that the object is moving at the same speed without any acceleration. Positive constant velocities are above the x-axis, and constant negative velocities are below.

On a V/T graph, when the line touches the x-axis,

the object is at rest.

On a V/T Graph, what does the slope give us?

the acceleration of the object, indicating how quickly the velocity changes over time.

On a v/t graph, a line heading towards the x-axis is

slowing down, and a line heading away from the x-axis is speeding up.

How can you determine the displacement of an object on a V/T Graph?

You can determine the displacement of an object by calculating the area under the velocity-time graph, which represents the total distance traveled in a specific time interval.

What does a curve on a V/T graph represent?

A curve on a V/T graph represents a non-constant acceleration.

What is a changing acceleration called?

A jerk. For a changing acceleration, you have to use calculus…

On an A/T Graph, how is a constant positive acceleration, at rest, and constant negative acceleration represented?

A constant positive acceleration is represented by a horizontal line above the x axis, while at rest is represented by a horizontal line on the x axis, and a constant negative acceleration is represented by a horizontal line below the x axis.

What is a situation where an object’s acceleration is positive, but the object slows to a stop?

This situation occurs when an object is moving in the opposite direction of its velocity. An example is when a car is moving backward and the driver applies the brakes, resulting in a positive acceleration while decreasing speed.

How to find an objects total displacement on a PT graph?

Subtract the starting position from the final position (delta x = xf - xi).

How to find average speed on a PT Graph?

To find average speed on a position-time (PT) graph, divide the total distance by the total time taken (average speed = total distance / total time).