All High School Physics Resources
Example Questions
Example Question #111 : Linear Motion
The fastest pitch recorded in baseball was a fastball. The distance from the pitcher's plate to home plate is . How long did it take for the ball to reach the batter?
To solve this problem, we use the relation between velocity and time:
We can rearrange this equation to isolate the variable for time:
Use the given distance and velocity to solve for the time.
Example Question #15 : Understanding Distance, Velocity, And Acceleration
Which of the following is a correct measurement of velocity in SI units?
Velocity is a vector measurement of displacement per unit time. This means that it has both magnitude and direction, according to the direction of the displacement.
The standard unit for displacement is meters and the standard unit for time is seconds; thus, the SI unit for velocity is meters per second. Any standard measure of velocity will be given in meters per second, with a corresponding direction of action.
Example Question #12 : Understanding Distance, Velocity, And Acceleration
You are given a graph of velocity vs. time. How can you find the change in displacement for a particular time interval?
The displacement is the total area under the curve of the graph
The displacement is the area under the curve for the given time interval
The displacement is the average slope during the given time interval
The displacement cannot be determined from the graph
The displacement can only be found when the velocity crosses the x-axis
The displacement is the area under the curve for the given time interval
Velocity is equal to a change in displacement per unit time. Consider a basic velocity vs. time graph that depicts a constant velocity, given by a straight horizontal line. How can we determine the displacement during a given time interval? Use the kinematics equation:
Acceleration will be zero, allowing us to reduce the equation. We can also assume that there is zero initial displacement.
So, the displacement will be equal to the velocity multiplied by the time. In the graph, velocity will be represented by the vertical location and time will be represented by the horizontal location of any point. Displacement will be equal to the height of the graph times the width of the graph, or the area of the rectangle created by the constant velocity over a unit of time.
Though this is just one example, displacement will always be equal to the area under the curve of a velocity vs. time graph.
In calculus terms, velocity is the derivative of the function for displacement in terms of time. To find the displacement, one must take the integral of the velocity function. The result is the area under the curve of the velocity function.
Example Question #21 : Understanding Distance, Velocity, And Acceleration
You are given a graph of displacement vs. time. Which of the following ways can be used to determine velocity at any given point?
The velocity is the slope of the line at any given time
The velocity is the y-intercept of the graph
The velocity is the total change in displacement over the total time
The velocity cannot be determined from a graph of displacement vs time
The velocity is the area under the curve for any time interval
The velocity is the slope of the line at any given time
The important thing to note is that the question asks for the velocity at any given point. The average velocity will be equal to the total displacement divided by the total time, but the question is asking for the instantaneous velocity.
Velocity is calculated by a change in displacement over a change in time. In a displacement versus time graph, this is equal to the slope.
This tells us that the slope at a certain time will be equal to the velocity at that time.
In calculus terms, velocity is the derivative of the function for displacement in terms of time. What this means is that at any point on the graph, the instantaneous slope is the velocity for that given time. To determine velocity, one must find the slope of the line at that particular time interval.
Example Question #112 : Linear Motion
A mass moves a constant velocity, , for a certain amount of time, . How far does it travel?
The relationship between velocity, distance, and time is:
We can multiply both sides by to see solve for the distance traveled, in terms of the time and velocity.
The product of time and velocity, , will give us the distance we are looking for.
Example Question #21 : Understanding Distance, Velocity, And Acceleration
Derek rolls a ball along a flat surface with an initial velocity of . If it stops after 12 seconds, what was the acceleration on the ball?
Since the ball starts with a positive velocity and ends at rest, we can predict that the acceleration will be negative. Using the values given in the question and the equation below, we can solve for the acceleration.
Example Question #22 : Understanding Distance, Velocity, And Acceleration
An object starts sliding along a floor at a speed of . After , it is observered that the object is sliding with a speed of . What is the average acceleration of the object?
Notice that at the beginning and at the end of the problem, the velocity of the object is . Acceleration is . Since there is no change in velocity, acceleration is calculated as , so the acceleration is .
Example Question #22 : Understanding Distance, Velocity, And Acceleration
A balls starts at rest, then begins to move with a negative acceleration. Describe the motion of the ball.
It is lifting off of the ground
It is slowing down
It remains at rest
It is moving backwards
It is beginning circular motion
It is moving backwards
Acceleration is a vector. This means that positive and negative signs are used to help us understand the direction of motion. If something has a negative acceleration it CAN mean that it is slowing down, but not always. Negative usually means that an object is moving to the left, down, or backwards. If the ball begins from rest, and has a negative acceleration, then it is gaining a negative velocity. This simply refers to a velocity in a negative, or backwards, direction.
Example Question #121 : Motion And Mechanics
An object starts at rest and reaches a velocity of after seconds. What is the average acceleration of the object?
The relationship between acceleration and velocity is:
Acceleration is equal to the change in velocity over the change in time. If the object starts from rest, then we can set up an equation to solve for the change in velocity.
Using the terms from the question, we can see that the acceleration will be equal to the final velocity divided by the time.
Example Question #26 : Understanding Distance, Velocity, And Acceleration
You are given a graph of velocity vs. time. Which of the following ways can be used to determine acceleration at any given point?
The acceleration is the total change in velocity over the total time
The acceleration is the area under the curve for any given time interval
The acceleration is the y-intercept of the velocity vs time graph
The acceleration cannot be determined from the graph
The acceleration is the slope at any particular point in time
The acceleration is the slope at any particular point in time
The important thing to note is that the question asks for the acceleration at any given point. The average acceleration will be equal to the net change in velocity divided by the total time, but the question is asking for the instantaneous acceleration.
Acceleration is calculated by a change in velocity over a change in time. In a velocity versus time graph, this is equal to the slope.
This tells us that the slope at a certain time will be equal to the acceleration at that time.
In calculus terms, acceleration is the derivative of the function for velocity in terms of time. What this means is that at any point on the graph, the instantaneous slope is the acceleration for that given time. To determine acceleration, one must find the slope of the line at that particular time interval.